Is it permissible for a woman to request in her will that no one wash her upon her death except her husband, and that no one else see her?

It is permissible for either spouse to wash the other, based on what has been narrated from the Companions like Abu Bakr, Ali, and Fatimah (may Allah be pleased with them), and based on what Aisha (may Allah be pleased with her) enjoined, that his wives should wash him.