It is permissible for one of the spouses to wash the other after death
Question

Is it better for a man to be washed (after death) by his wife or by other men?
Praise be to Allah.It is OK for a woman to wash her husband if she is knows how to do that. ‘Ali (may Allah be pleased with him) washed his wife Faatimah (may Allah be pleased with her), and Asmaa bint ‘Umays washed her husband Abu Bakr al-Siddeeq (may Allah be pleased with him).