Mrs Harbinson and the Harbinsons' 29-year-old daughter both suffered serious injuries.
Mrs Harbinson was still in a serious condition in Hawke's Bay Hospital's intensive care unit yesterday.
The daughter, however, was in a stable condition in one of the hospital's wards.
The police's eastern serious crash unit is continuing to investigate the incident.
But police said yesterday speed did not appear to have been a factor in the smash.
"This is a tragedy for the family involved and a sad way to start the year off on Hawke's Bay roads," Senior Sergeant Clint Adamson of the police eastern district command centre said.
"Police would like to remind all drivers to take care as they travel around our district and to remember the basics - travel at a safe speed for the conditions, wear your seatbelts, don't drink and drive, and take a break if you are feeling tired."