Professor is upset about student comments about her lectures. What should I do?
What should I do?


Honestly? I suggest that you sympathize courteously, but do nothing else:


She's a grown woman and an experienced academic, she doesn't need you to handle frustrations from student feedback.
You (likely) no longer work at the same university as her.
You're not a close personal friend of hers.
You don't have a good idea of what actually goes on in her classes these days, nor what the student body is like overall.
It is generally the case that students don't complain repeatedly and en masse about a course just for the sake of complaining and regardless of anything else. There's probably something that's wrong with the course (perhaps not even with her behavior) that you just don't know about.


An alternative to doing nothing would be: Suggest that she ask a relevant question here on  academia.stackexchange.com. We could obtain more information which you don't have rather than help her via a third party.