Is it permissible for a woman to allow non-mahram men into her home in the absence of her husband and mahram relatives, even if they are known for their piety and righteousness?

A woman is permitted to host her paternal uncle and maternal uncle in her home with her husband's permission, as long as no fitna (temptation/discord) is feared, because they are among the mahārim (unmarriageable kin) mentioned in the Quran. As for non-mahārim, it is not permissible for a woman to allow them into her home in the absence of her husband or a mahram. This constitutes forbidden khalwa (private seclusion), and even if they are righteous individuals, everyone is susceptible to fitna. The Prophet, peace and blessings be upon him, forbade entering upon women and secluding oneself with a non-mahram woman, for "the in-law is death," because Satan is the third party between them. It is not permissible for anyone to seclude himself with a woman with whom he has no mahram relationship.