I am sorry to hear about your mother in-laws condition.
Your mother in law is a terminal case that seems to be nothing can be done for her in terms of medical management.
Not urinating for 3 days is either a sign of organ failure or if she do not have any fluid intake, then an output cannot be expected. Water pills won't help in that situation. Bleeding she has is in association to her liver disease.
She is dying for sure and you have the right to say that you cannot just let her to die like that. At least, she has to be comfortable and all possible means should be done to let her to die in comfort. She has to be kept clean, dry and comfortable. She needs to have pain reliever if there is any pain. If she is unable to take anything orally, at least she has to be given some other sort of providing her fluids and nutritional needs, either by intravenous fluids or nasogastric tube.
At this stage, home is the best place for her as long as there are significant family members who can care and stay with her until her final moments. I believe your mother in-law would love to have her final moments at home with all the loved ones around. But at least, there must be a healthcare provider to check on her to assess what is going on and provide some possible supportive measures or symptomatic treatment so as not just leaving her to die in one corner possibly with all the discomfort. If you can arrange for a healthcare provider to do home visit at least, that will be a good idea.
Well, that is my opinion as a nurse who had handled terminal cases similar to your mother-in-law.
If she is able to drink then the absence of urine output is an indication of an organ failure ,her kidney is failing most possibly due to over diuresis. With both liver and kidney now considered in failure, we cannot tell how she will cope up. It all depends on her system's tolerance. If she is not receiving any supportive treatment now for her liver, complications can set in anytime which include coma. The same thing with the kidneys, if body wastes (urea and creatinine) blood levels continue to rise, complications can progress rapidly. Other organ failure can follow such as heart failure. When will that happen, we cannot presume without at least any laboratory blood tests to see how are her organs system doing.