It started when my mother had a surgery for breast cancer. She was a very active person, but now her body doesn't allow her to do as many things as before. She can't play music, or do much work. She can't go to the gym and lose weight. She was already psychologically weakened, due to taking care of my bedridden grandma for years (she is dead now). So inactivity is killing her. She barely holds herself together sometimes. The rest of us are quiet nerd types so we can't easily create the energetic atmosphere she suddenly needs.
Also, my father won't understand the size of the problem, thinks she's over-reacting...and sounds like he's starting to give up on her case. If they went out sometimes it would help, but we're pretty poor, so it's not easy to find great stuff for them to do together outside the house. My bro is in his teens, and studying for uni entrance exams. He's really loud and often quarrels badly with my mother, despite actually loving her (it's how he is) Seeking chances for quarrel for silly things, never taking a step back, and not understanding she really can't take it anymore after the surgery (I find her secretly crying after some quarrels) Me and mom have tried to talk to both separately bot none of them understand.

I'm really worried about my mother, she sometimes sounds like she wants out. But I don't know how to make others understand and listen. And we can't just create a lively atmosphere in the house 24/7. What can I do?