Q. Can a woman be a Shomeres and watch over a deceased? Can the wife of the deceased do so?
A. Poskim disagree whether women can do shemira even for other women. Beer Sorim (2: 77) prohibits, while others permit for women (Zichron Meir on Avelus p. 218).
Horav Shlomo Miller’s Shlit’a opinion is that in need, when no men are available they can do shemira even for men.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a.