What do the movements of her hands and feet mean?

Realtime, it sounds like "delirium" or either nervous energy. If this is bothering your Mom, then ask her primary doctor for some meds to calm her down.

Thanks, Freqflyer. She isn't aware of the movements, so they don't bother her. It's just that she's 96 and I don't want to overlook a symptom of something that needs treatment or that's a warning of a future problem. It could be nervous energy. She used to have severe anxiety problems, but I haven't seen any evidence of that for over a year. I'll discuss it with her PCP at the next appointment, in two weeks. As I understand delirium, it wouldn't be that, since she's in very good shape cognitively.

Look further, tardive dyskinesia affects "extremities" meaning both hands and feet.

There are educational videos of TD on YouTube. Poor souls are always moving, from mild (just small mouth movements) to whole body involvement. Hands and feet included.

Pam, Thankless -- Thank you! Don't know how I missed that.

And yes, the PCP (we visited a couple of days ago) confirmed the tardive dyskinesia. New PCP --- her long-time doctor gave up his practice a few years ago, his replacement moved out of state, but at last we have a delightful young guy that my mother adores. At 96, she still likes to flirt, and he responds beautifully. Knows exactly what she needs from him. (When he met her for the first time last week, he started out by saying, "Hey, they told me you were 96 so I was expecting a little old lady! You look great!") I'm so relieved to have someone to ask questions of without struggling through a specialist's time constraints.