What can be done about my verbally abusive Dad (60)?

My father has been very ill for a long time. He has poly-cystic kidney disease which is hereditary. He is not diabetic, nor a past with drugs or alcohol. He is, unfortunately, extremely verbally abusive. He has always been that way, he has no friends and views the people of this world as idiots and is very vocal about his opinions on everything including his doctors. My stepmother recently retired and has been doing her best to care for him, but he constantly criticizes, screams at her and calls her awful things. He demonstrates sociopathic tendencies and has since I can remember, even when he was perfectly healthy. He is unable to care for himself, but refuses help from anyone except for my stepmother or myself. I live hours away and cannot be available to them nearly enough. He yells for her through out the house at all hours of the day and night, and is just so nasty and mean to her, it is a wonder that she hasn't left, but she is exhausted especially emotionally, she cries whenever she describes how he treats her, and it's just too much to bear. She is a very hard working and loving wife, but he talks to her like she was put on this earth to make him miserable, and he does it so viciously, it makes me want to scream at him. He tries to make me side with him when they argue and of course I can't because he is in the wrong. Physically he is completely incapable of causing her any bodily harm, but he is obstinate, mean, and cruel towards her, and worst of all, he is lucid. He says that she is horrible to him, but I've witnessed first hand how she cooks for him and he takes one bite, and pushes the food away in disgust while saying "tastes like s#1t!" and of course it tastes very good because she has always been a very good cook. He doesn't ask her to do things, he orders her to do things, and of course he is never satisfied even when she does the tasks to the letter. He constantly calls her a liar and a B*. If he were healthy I would punch him in the mouth for the things he says to her, and to me about her whenever I come to visit. She's at her wits end. I've told her that if she chose to divorce him, no one would blame her at all, she is still in good health, she has grand children by my step-sisters that are the most important thing in the world to her but she resides in Texas and her children and grand children are all in Virginia. My older full blooded sister now lives in Washington state so I'm the only one left around but I live and work a full time, actually more than full time( usually 60 hrs plus a week) job in another city 4 hours away. Is there anything she can do for relief from this nightmare? I come up when they call try to give her a break, sometimes she will go stay with one of her sisters, whom he can't stand, he says awful things about her entire family, too. I try coaching him to be nicer but he says she's mean to him and deserves worse. I know she snaps back at him, I've seen it, but being at some ones beck and call 24/7 with all of the appreciation of a hated and loathed enemy is wearing her out. He refuses all outside help and care and is abusive to hospital staff. It's just too much for one person to deal with alone and I'm worried that the emotional toll is going to end up affecting her in a permanent way. I know he's in constant pain, but he was always mean and petty, it's just worse now, and I don't know if there is anything that can be done but if there is anything to relieve her from this monstrous situation, legally and compassionately, I would like to hear about them. I won't lie, I use to live much further away, and I moved back to the area when it seemed he was not going to live for more than a few years. I wanted to try and repair my relationship with him, to offset potential feelings of regret, but he got much better and so I moved away again but now that his health is in steady decline, every hospital trip for his lungs and his heart and his broken pelvis from falling, he gets so weak and frail and looks like he's about to die and says so himself, he just comes back meaner and more awful. It's like the devil is afraid to have him. I know these are awful things to say about your father, but they are true. Unfortunately it seems there isn't a way to put him in hospice or a home without his consent, not that I would wish to subject anyone in those fields to his nature, but what if anything can be done to protect her?