How old is she?
In in all honesty..from your heart...do you think she should still be driving?
85...she's ok, she does not drive at all in rush hour, rain, snow and/or bad Wx or at night. You would have to meet her to judge her. I'm sure her Dr. would tell her to stop if she thought she should.
I had an Aunt who drove from Mineappolis/St. Paul every Summer to stay with my Granddad and she drove this when she was in her 90's!
My Father was still flying his plane at 85. Here's a picture of him when he was 80 years young putting gas in YPA.
You have to look at these things on a case by case basis.
Railton