Don't Tell Mom the Babysitter's Dead (1991)

Single mother goes away for the summer. The kids are first delighted but then find that Mom has hired the sitter from hell to stay with them. When the sitter dies of a sudden coronary they deposit the body at a mortuary only to discover all their summer expense money was in her purse. The kids must find a way to survive the summer without mom or her money. This means actual work!