Treatment of kidney failure in an 80 year old is tough. Depending on the severity of the renal failure, it could be simply providing diuretics and other drugs to help stave off complete renal failure. However, if her one remaining kidney has essentially failed completely, the only remaining treatment is dialysis. Without dialysis, the prognosis is death (within a few days to weeks, depending on how far along things are), typically from a build-up of potassium and eventual cardiac arrest. There is no pain or suffering from kidney failure except perhaps some itching from the build up of toxins. When people die from kidney failure, they tend to drift off into a coma, and then subsequently die from the cardiac arrest. Now, as far as dialysis is concerned, this is a serious issue that she needs to consider. You are essentially hooked up to a machine for 4 hours a day, 3 days a week. There are complications depending on the type of dialysis access used (i.e. where are the needles placed), but people can survive for a long time on dialysis. Sorry to hear about your MIL (and if I was too blunt). But, those are the facts. Best wishes.