In days of old when the dead were laid out in the parlour of the family home, people, either out of respect or superstition, draped all the mirrors and windows of the house with black crepe. Professional "funeral" operators would begin to prepare for this ahead of time as they noted that there were local people nearing death's door. This gave birth to the term, "crepe hanger" to people who are compulsive worriers, anxious about things that have not yet happened. This "tradition" also gave birth to the use of black crepe for the manufacture of ladies’ mourning dresses, men’s hat bands and arm bands, and funeral wreaths
Mothers who are constantly worried and over anxious about their children, husbands etc when they don't get home on time, and in their mind's eye see them in an accident, hospitalized, dead and themselves standing over a gravesite could be considered "crepe hangers."