A missing Victorian woman has been found safe in Yass after she and her husband sparked a search in New South Wales and Victoria in what police say is the most bizarre case they have seen in decades.

Key points: "Stressed" family went separate ways in rural NSW during holiday

"Stressed" family went separate ways in rural NSW during holiday Mother found and hospitalised with stress-related health concerns

Mother found and hospitalised with stress-related health concerns Search continues for father who is believed to have run from police in Victoria

Mark and Jacoba Tromp from Silvan, east of Melbourne, left their home with their three adult children to go on a trip on Monday.

The couple was separated from the children — who did not want to continue with the holiday — in the New South Wales central tablelands and reported missing on Tuesday.

A member of the public took Ms Tromp, 53, to Yass hospital on Thursday morning, and she has been assessed for stress-related health concerns.

Meanwhile, the search continues for 51-year-old Mr Tromp.

Police believe he is in north-east Victoria after the car the family was travelling in was pulled over at Wangaratta on Wednesday night.

When the grey Peugeot station wagon was stopped by police, the driver, believed to be Mr Tromp, ran away into a nearby park.

'Fair degree of paranoia involved'

Despite an extensive search of the area with the help of the Victoria Police dog squad, he was not found.

After the children left their parents, all three went their separate ways to get back to Melbourne.

One daughter has been hospitalised in Goulburn with stress-related health issues.

Detective Senior Sergeant Kevin Coghlan of Wangaratta Police said he believed the family had investment properties in the area.

"My understanding is there's a fair degree of paranoia involved in what they're doing and why they're doing it," he said.

"They left Melbourne with a large degree of cash in their pocket.

"As to the extent of how much they've spent I can't tell you."

Family under stress, son says

The couple's son Mitchell Tromp said the family — who operate a redcurrant farm in Silvan — were under stress and "fleeing something".

He said the couple were paranoid just before they disappeared.

"It was like a movie, I've never seen anyone act like this," he said.

"It was a build-up of different, normal everyday events, pressure and it slowly got worse as the days went by."

Mark Tromp is still missing, police say. ( Supplied: Victoria Police )

Mitchell said his parents' behaviour was out of character and he wanted to see his father return home.

"I really want my Dad to be found, if everyone out there can keep an eye out for him," he said.

"He's not dangerous, he's my mate, he's my father. I love him, I just want someone to find him so we can bring him home."

Sergeant Mark Knight has described the incident as "the most bizarre case in 30 years".

He said when he went to the family's home on Tuesday he found the couple's personal possessions such as bank cards and mobile phones and paperwork all over the house.

"This is a really unusual case," he said.

"We know the family was obviously traumatised by something. We didn't know what it was."