Well okay, what she needs then is a car with a long door, high seating and lotsa legroom. Basically sounds like she needs to get in butt-first (if you will excuse the familiarity), then rotate herself into the car. So the seat can't be too low, and the A pillar cannot be so close as to interfere with her swinging her legs in.
So anyway, you can eliminate any car who's roofline is too low and where the driver's door is pretty stubby. Ironically, maybe a coupe would be better, as the front doors are often longer.
It's either that or some monstrosity SUV, seems to me. But there the seating might be too high for her.
This may be a task requiring trips from one showroom to another.