Story highlights PLO holds Israeli government responsible; Israeli official says Israel "absolutely" condemns attack

The woman's 4-year-old son is the only survivor, but he is in critical condition

The whole family was burned in the July 31 "price tag" attack

Jerusalem (CNN) A Palestinian mother severely burned in an arson attack that claimed the lives of her husband and toddler has died of her injuries, a family member said Sunday -- leaving the family's 4-year-old son as the only survivor.

Reham Dawabsheh had been in critical condition since the July 31 attack with burns to 80% of her body. Her brother-in-law, Nasser Dawabsheh, told CNN she died Saturday.

The couple's other son, Ahmad, was also burned over 80% of his body and remains in critical condition.

Authorities found the words "price tag" written in Hebrew on the walls of the family's house in Duma, said Luba Samri, a spokeswoman for Israeli police.

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