My dad studied hard at age 92 to pass the written test, and did fine. Then came the driving test, tough already given that he had to find the car in the DMV parking lot, and the officer flunked him for driving way too slow...25 in a 45, 40 on the 65 MPH freeway.

I really feel for the officer, that must have been a scary ride. Dad remained convinced that it was prejudice, that the young people just didn't like the elderly, but I retained control of the keys and within a couple of months moved him in with me. He still complained about wasting his perfectly good driving skills, but by then sometimes mistook me for HIS dad and had trouble understanding how our home 800 miles inland was not at risk from tsunamis.

Good luck, and remember to give yourself the benefit of every doubt. There's no reliable manual for this kind of care and you have to work it out step by step. Remember also that it is normal to have VERY negative thoughts and feelings about your declining parent, don't beat yourself up and get a little counseling if possible;)