How much visiting is too much?

My mom came to visit me out of state and was admitted to hospice care right away. She is a 5 year lung cancer survivor and it has likely spread to her liver and spleen. Before her visit to my home (planned to give my dad a break as he wasn't caring for her well) the oncologist wrote her a hospice presription. She has de coined quickly in the last 40 days. My husband and I are now feeding her, dressing her, toile ting her, changing the Depends, and brushing her dentures as she cannot do anything on her own. She eats and drinks a bit but if we don't help she gets very little food or drink.

Relatives are coming in from out of town and are wanting to see her and it's getting clear that it is very hard on her. One visiter is actually my sister who is king of toxic and very over bearing. I'm afraid she will bring up topics that are upsetting to my mom Bc she does this over the phone. Like she questions my mom about morphine that I give for pain. My mom has dementia and doesn't remeber it so my sister gets upset at me and says mom didn't need the morphine. The other visitor that is coming is my uncle who is not even arranging his plans with, he has done it through my aunt. I sense he isn't talking with me because we have recently vehemently disagreed on politics recently over facebook. However, I'm fine with his own views but I feel he isn't speakjng to me. We were at a family party last year and he all but ignored me until I approached him. The thing is that its rude to not be speaking me and I feel he is unwelcome if he can't even coordinate plans directly with me to see my mom. Also, this is very rough for us. My father and three siblings are not supporting me in any of he care financially or by being here. Two of my siblings aren't working and they have washed their hands of this. My father isn't helpung as he has his own issues and I am helping him from another state paying bills etc. my siblings will not even travel with him to see my mom here during her last days. I am at my wits end and having trouble making sense of people's irrational behavior like my uncle not speaking to me soninjustvwanted don't want to even deal with it and I am ticked off about it. Am I being overly reactive? Does it really matter if he won't speak to me? What obligation do I have to them and what is a good way to limit their visits? Please help!