What is the expiation for a wife who occasionally did not respond to her husband's call to bed due to exhaustion or mood, or due to his contagious illness at the end of his life, given her remorse and desire to atone for her sin after his death?

It is obligatory for the wife to obey her husband in intimacy. It is not permissible for her to refuse unless there is a valid excuse, such as illness, menstruation, an obligatory fast, or harm resulting from intercourse. If her refusal is due to an excuse, there is no blame upon her. However, if it is without an excuse, then she must repent, feel remorse, supplicate, and seek forgiveness for her husband.