At my wits end!

My mother passed away in 2006 and my stepfather lives next door . Since my mother has passed he has married her sister and so far has given almost everything to her and his other daughter. Ever since my aunt has moved in with him in the passed 3 years i have come to believe that she is over medicating him to the point where he doesnt even remember leaving his room and falling on the kitchen floor and broken his hip. Since then I believe she is ivin him way more medication then he needs cause of the simpe fact that she abuses presciption drugs herself and all she wants to do is sleep so she gives him 3 xzanex a day pus 2 sleeping pills at night. He is also in the beginning stages of alzheimers and now she wants him to sign over the house and my mothers car. She tells people that it is his idea but he doesnt have a clue half the time. My question is this is there anything legally i can do about this?