"He said,'Come with me, I'll take you to the car' and they were walking around and she got back in it."
Ms Luxford said the family now think their mother, who suffers from dementia, may have spent the past four days at the crash site.
They also believe she would not have lived beyond today had she not been found.
She said the area had been canvassed in a private family search but believe the crash site was well hidden from the road.
Ms Luxford said the family were indebted to the passing farmer who spotted the wreck on the remote Okirae Rd in Fordell.
She said all he saw was a shiny glint in the brush which he stopped to investigate.
"Man, he's a hero. We really want to thank him for bothering to do something," she said.
Their injured mother was now resting in hospital. She was severely dehydrated, bruised and sunburnt.
But she had started eating and the family was hopeful she would make a swift recovery.
The family were overwhelmed at the support New Zealanders had shown to the family.