Is it permissible for a Muslim widow working as a cleaner in a hospital to clean and arrange the Christian funeral hall, including placing the cover on the table and hanging the cross, knowing that there is no one else to do this work?

A woman is not permitted to work in a job that involves assisting in the display of symbols of disbelief (kufr) and glorifying polytheists. However, if she can avoid prohibited acts, such as hanging a cross, then there is no impediment to her continuing in that work.