Ghusl is a washing after death. Some scholars say that it is not permissible for a husband to wash his wife because death is equal to a divorce. However, this view goes against the Sunnah. Hence, it has no importance in religion. According to ‘Aa’ishah (may Allah be pleased with her), who said: If I had known beforehand what I know now, no one would have washed the Messenger of Allah (blessings and peace of Allah be upon him) but his wives.
Most companions of the Prophet PBUH did believe that it is permissible for a man to wash his wife’s dead body, and vice versa.