Oh, Harmacy, what an ugly brother! Were I you I would do a couple things; see if I could find myself a counsellor so I would have someone to think on and know was in my court and I'd stop arranging much with your brother; not let him know when you will be visiting your mother or helping at the house and I would pick odd days/hours to check on the house, etc. If he comes while you are there, I would be the one to leave without speaking, etc., if he tries to start something just say something like, "I have nothing to say to you" and leave.

If I were still very upset, these sorts of tactics weren't working, I would try to make it a game to upset him in a way that was amusing to you. I would start agreeing with the disagreeable things he says :-) and not let them affect you. "Get back on your medicine" would be responded to with a cheeky smile and "Thanks for the suggestion!" and then you leave (or go about doing whatever you came to do, if he wants to follow you around the yard while you mow, he's the one who would look ridiculous?). If he's "waiting" for you, again, the bright smile and "Brother, dear, how good to see you!" as if you are in a play for the neighbors? When he sees he cannot rattle you he probably will stop. Talk to your mother's nurses/caretakers and let them know he appears to be upsetting your mother and can they catch him at it and take him down or not let him talk to her on the phone as much (say she's sleeping or something)?