2-year-old boy whose Yemeni mother fought Trump's travel ban to be with him has died Abdullah Hassan, 2, died Friday after being reunited with his mother.

Abdullah Hassan, the 2-year-old boy whose mother fought against Trump's travel ban to get a U.S. visa to be with him, has died.

"We are heartbroken. We had to say goodbye to our baby, the light of our lives," Ali Hassan, Abdullah's father, said in a statement Friday. "We want to thank everyone for your love and support at this difficult time. We ask you to kindly keep Abdullah and our family in your thoughts and prayers."

Abdullah's mother, Shaima Swileh, was denied a visa to travel to the U.S. for more than a year because she is from Yemen -- one of the countries on which the Trump administration imposed travel restrictions. Swileh’s husband and son are both U.S. citizens, and Ali and Abdullah had been in the U.S. since October as the toddler received treatment for a rare brain disease at the University of California San Francisco's Benioff Children's Hospital.

Swileh was only granted a visa on Dec. 18 after attorneys for the family filed a lawsuit in federal court. She arrived in the U.S. and was reunited with her husband and son, but by then, Abdullah had lost consciousness, said Banan Al-Akhras, an advocate for the family who works with CAIR and the family's attorney.

Al-Akhras waited outside of the hospital room as Swileh saw Abdullah for the first time.

"It was heartbreaking. You could hear her emotional response through the door ... She broke down. I can't imagine what it would be like to see such a deterioration within a few months," Al-Akhras told ABC News. "It was very visceral -- she wasn't holding back anything. She was obviously and very clearly in pain.

"The last time she saw him he was awake and breathing and moving, and that kind of thing, and just a few months later, he's completely reliant on machines," she added.

Swileh spent the next nine days with her son before his death struggling to come to terms with losing him, the family's attorney, Jennifer Nimer, told ABC News.

"That is, to me, the most heartbreaking thing about this entire situation. She could have been here with him for the past few months, and there was just no reason for that not to happen," Nimer told ABC News. "It's devastating to lose a child, but I can't even imagine how she is feeling knowing that she was away from him for the majority of the last two months he was hospitalized. I don't think there are any words to describe how that must feel for them. And that's something that she will probably never get over. Not being able to be here to do everything she could to comfort him -- that's something that is obviously extremely traumatizing."

The Trump administration has defended the policy as one to combat terrorism and keeping the "country safe." After the Supreme Court upheld the latest iteration of the ban earlier this year, Trump said in a statement the ruling was a "tremendous victory" for the American people.

"In this era of worldwide terrorism and extremist movements bent on harming innocent civilians, we must properly vet those coming into our country," he said in the statement.

A memorial service was held for Abdullah Saturday at the California Islamic Center in Lodi, and he is being laid to rest at the California Islamic Cemetery, the Council on American-Islamic Relations, Sacramento Valley office said in a statement.

Abdullah suffered from epilepsy and hypomyelination, a neurodegenerative disorder, Nimer said. While he received treatment in the U.S., Swileh was unable to be with him for months, though she tried several times to have her visa waiver request expedited.

Swileh was finally granted a visa after attorneys for the family filed a lawsuit in federal court Dec. 17 against Secretary of State Mike Pompeo, Department of Homeland Security Secretary Kirstjen Nielsen, Assistant Secretary of State for Consular Affairs Carl Risch and Consul General at the U.S. Embassy in Cairo Lisa Vickers, among others.

The contents of the lawsuit have not been made public, but it sought immediate relief in the form of the visa waiver, which has been granted, as well as damages, Nimer said. A State Department spokesperson declined to comment to ABC News on the lawsuit filed earlier this month, citing department policy to not discuss pending litigation.

Nimer said that rather than amending it, she moved to voluntarily dismiss that lawsuit late last week because the visa had been obtained. Nimer said the family plans to file a lawsuit in California, where Hassan and Swileh live, against the same parties and seek damages.

"Getting damages from the government is not easy to do, but the important point about is that their behavior was so egregious, I just don't think it should be let go," Nimer said. "Whether we're ultimately successful or not, I think bringing attention to the issue is important. There has to be some changes in the waiver process, it just can't be like this."

Nimer told ABC News earlier this month that Swileh was first interviewed by U.S. consular officials for a visa in November 2017, when an injunction on Trump's ban had been put in place, so she could travel with her husband and son as they sought treatment for him.

The U.S. Embassy in Cairo did not make a decision on Swileh's visa until last December, when they denied her on the grounds that the ban on travelers from Yemen was in effect once again after the Supreme Court allowed the ban to go into effect on Dec. 4, 2017 even as legal challenges to it made their way through the courts.

Swileh applied for a visa waiver, and requested that it be expedited several times, Nimer said, adding that the family emailed embassy officials 28 times to check on the status of her application and explain how dire Abdullah's health had become.

"They repeatedly emailed, begging and pleading and detailing that their son was getting sick, and he was getting worse, and we have to travel. They mention that he was still breastfeeding and didn't want to be separated from his mother," Nimer said. "And every time the answer was simply, 'Your case is in administrative processing.' You can't even get a human response."

Finally, Hassan decided to bring Abdullah to the U.S. alone in October to get medical treatment. But Swileh was still waiting on the visa waiver to join them, even as Abdullah's health worsened, Nimer said.

Hassan began working with CAIR to try to raise awareness about his wife's case. Nimer began representing the family on Dec. 14, sending inquiries to the U.S. Embassy in Cairo and the State Department's LegalNet, a resource for attorneys.

"We specifically said, 'This is a matter of life and death at this point, and it needs to be expedited.' And the embassy's email was exactly the same, 'It's in administrative processing.' And we actually told them in that email we were planning to file a lawsuit, just kind of hoping that would prompt them to get moving on it," Nimer said.

Nimer said the family has "suffered needlessly" over more than a year, and especially during the past two months as Abdullah's health worsened in the U.S.

"They lost two months together as a family during the most important time, and there is just no way to ever fix that," Nimer said. "I hope that this case can be a catalyst for some type of change. There is no transparency, there is no real process here with [the waivers]."

Al-Akhras said she hopes the family's case brings people together to push the government to end the travel ban entirely.

"It's sad that it took a little boy's life to shed some light on this racist policy," Al-Akhras said. "It affects people of all different ages from all walks of life ... You have people who are in very terrible situations, war situations, they don't have anywhere to turn."

"This is his legacy at this point. He didn't pass away in vain," she added.