How long can person live without dialasys?

my mother's kidney function is only 10% left she is 74 year old and very weak. My mom is really suffering from sharp pain in legs sometimes, vomiting, itchy skin cant sleep at night without morphine pills. Last time she went to doctor was April 7th, she can hardly walk due to weakness. she is on bed since 1 year now. My mom don't want dialysis and she is too old for kidney transplant, even doctors say dialysis is like torturing the person too and she is too weak for that. How long she could live like this? It is very hard to see my Mom suffering she has been very sweet lady all her life to everyone who know her.