Depending on the episode, the police called Blanche to inform her that her husband was killed in a car accident, or her husband died from a coma brought on by injuries from a car accident.
When the girls refer to the house, the address is quoted as either 5161 or 6151 Richmond Street.
As with any long-running show there are many inconsistencies between episodes. Characters' life histories, their birthdays and ages are reported differently from time to time as the writers invent new stuff for them that wasn't thought of when the series began. "Facts" are altered to fit the jokes, and a good deal of leeway is allowed.