Salah by someone suffering from memory loss

Q: My father has been suffering from memory loss since two years, and he is now seventy five years old; and is unable to offer Salah (Prayer) in the right way or to remember the number of Rak'ahs (units of prayer) he offers unless someone reminds him. As for myself, I offer Salah in the Masjid (mosque) and leave him to pray at home. Furthermore, he did not fast any of the days of last Ramadan, and as a consequence I fed a needy person for each day he missed. My question is:Is feeding a poor person for every missed day valid or not?Is it possible for me to stay at home to perform Salah with my father in congregation?When he is awakened to perform Fajr (Dawn) Prayer, he says that he already offered Salah although we know that he did not. Kindly advise me in this regard. May Allah save you.

(Part No. 5; Page No. 16)  A: If the reality is as you have mentioned, your father will be absolved from the obligations of Salah and Sawm because he has lost his mind. The Prophet (peace be upon him) said, There are three (persons) whose actions are not recorded: a sleeper until he awakes, a boy until he reaches puberty, and an insane person until he recovers his mind. Your father comes under this Hadith as one who has lost his mind.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.