In the answer to question no. 14016, we stated that it is permissible for one of the spouses to wash the other.
It is permissible for the husband to wash his wife after she dies, even if he did not consummate the marriage with her, because they are still spouses, based on the fact that they inherit from one another.
In al-Bahr ar-Raa’iq Sharh Kanz ad-Daqaa’iq (2/118) it says: The wife may wash her husband whether he consummated the marriage with her or not.
In at-Taaj wa’l-Ikleel Sharh Mukhtasar Khaleel (3/8) it says: One of the spouses may wash the other, whether he had consummated the marriage with his wife or not… because it is a permissible marriage and they inherit from one another (if one of them dies) before consummation of the marriage.
Al-Bahooti (may Allah have mercy on him) said: Each of the spouses may wash the other, even if death came before consummation of the marriage.
End quote from Kashshaaf al-Qinaa‘, 2/89
And Allah knows best.