What can I do if I want to take care of my grandfather instead of taking him to a home like my siblings want?

My grandfather (he adopted me so legally I am his son) recently went into the hospital. After 4-5 days he is acting crazy. By crazy I mean severe dementia. I stayed with him the whole week prior to him going to the hospital and saw him every week or so for a while before that. I am almost sure they are giving him anti-psychotics for his dementia. His bed has a beeper that if he gets up off the bed it goes off. What can I do about this? It is tearing me up inside. My aunt and uncle (legally my siblings) just say he is forgetful. They don’t think anything of it. I know they are going to try and put him in a home. I promised my grandma (legal mom) my grandpa and my biological father I would take care of him until the end. What can I do what are my options? This is very important to get back to me as soon as you can please. Tomorrow morning I am going to ask them all the medication he is on. I know my aunt and uncle and going to try and act like I have no say in the matter. I do right? Just as much as them correct? Thank you very much!