What is the way to stop a father from blaspheming the Divine Essence, taking into account that he is elderly and suffers from brain atrophy, and doctors have unanimously agreed that he is unconscious?

If reason is lost, a person is not held accountable, according to the hadith: "The pen has been lifted from three: from the child until he reaches puberty, from the insane person until he recovers, and from the sleeper until he awakens." As long as the doctors have agreed that your father has lost his awareness and intellect, then there is no blame upon him, and he cannot be restrained from what he says. Rather, one should pray for his well-being.