Is a woman who gave birth a minute before her husband's death considered his محرم, or has she become a stranger to him, making it impermissible for her to wash him?

It is permissible for a woman to wash her deceased husband if he dies while she is still married to him, even if she gave birth to her child moments before his death. The correct view is that she has the right to wash him even if she gives birth after his death and her 'iddah (waiting period) has expired, because her right to wash him is not forfeited by that; rather, it remains hers, like inheritance.