I am sorry to hear that your father has lost his battle with MND and please accept my condolences. You say you are uncertain about the benefits of stem cell treatment but the fact is that there is no proven cure by undergoing this procedure. The only medical "professionals" promoting the treatment are in it for profit. It sounds like your father underwent a huge physical, financial and emotional strain to experience a brief improvement in his quality of life, only to suffer a rapid decline.
I don't wish to appear negative or offensive as we all clutch at any straw when faced with MND but I do want to convey the message that stem cell treatment has a long way to go before it is proven both safe and successful.