<human>: Can you provide a brief overview of the text?

This has been going on for years and neither of us can take it anymore.

My grandmother likes to come over at random times of the week uninvited and unannounced, mostly for the purpose of lecturing my brother. My brother is dealing with an undiagnosed sickness (doctors are still trying to figure out what it is) and what at times seems to be depression. He's been having problems with dizziness, sleeping, and appetite. Most of the time he finds it best to lay down and nap, so we let him.

My grandmother's opinion is that all of his problems are in his head, so she'll just come over and interrupt his naps to tell him that. She'll lecture him on how he needs to be more selfless and that he needs to make more friends, and then she'll drag him downstairs to play the piano for her because that's something he's really good at. My brother is too nice to say no. 

I've asked my father to tell her to stop coming over in this way. If she could warn us first, even that would be better. She just comes in with a spare key. As far as I can tell he hasn't said a thing, and I don't think he will. Should I keep pushing him to say something, since it's his mother? Or should I step in and talk to her? If so, how?
<bot>: Grandmother is constantly coming over unannounced to bother my brother while he tries to get some rest. How do I get her to leave us alone?