Full brain radiation

My Mother had full brain radiation four years ago this April. She can't walk, she shuffles, she does not know when she uses the bathroom, she makes up stories, she never thinks she is hungry but when we put food in front of her she will eat, she is always thirsty, she hardly has any short term memory, very bad eyesight. Does anyone still have a parent or loved one with these side effects. Also I notice that each year these get progressively worse. What is the survival rate for a person in this condition. She had her first breast surgery at 50, her second at 70 and her brain at 75 and she will be 80 in July. We have round the clock help with her and she is still in her home. I would like to understand what I am to expect down the line. We try to take care of her as best as we possibly can and to keep her comfortable. Thank You