This is definitely worth consulting with several lawyers and determining how strong your case is. I am not a lawyer and I've never sued a medical doctor so I can't speak from experience and cant' advice you. But what I'd definitely do is to talk to lawyers about it. If they tell you you have a strong case, it is your decision to pursue it or not. I would pursue it, absolutely, but that's me.

In my humble personal opinion, this is a crime and, in a normally operating, not upside down society, this case would go to a criminal, not civil court. A doctor who damages a patient to the extent your mom was damaged should go to jail. I am so sorry your mom and you had to go through this hell. My heart goes out to you, truly.