What are the ways to atone for the sin of a wife not allowing her husband his conjugal rights, especially after the husband's death and the wife's relinquishment of her financial claims against him?

A wife's obedience to her husband in bed is obligatory. However, if she is afflicted with the magic of sarf (a type of magic that diverts affection) and is unresponsive to him, we hope she will not be held accountable for something beyond her control. She must repent, frequently seek forgiveness (istighfar), and perform righteous deeds, for Allah forgives the sins of whoever seeks His forgiveness and repents.

As for the right of a deceased husband, it can be atoned for by frequently supplicating for him (dua), seeking forgiveness for him, and giving charity on his behalf.