A Pup Named Scooby-Doo (1988)

S01E10 Ghost Who's Coming to Dinner?

On Halloween night, the group heads out for some trick-or-treating. When they arrive at the Johnsons' house, they discover that it's haunted by a ghost. Initially, they believe the spirit is friendly, but it turns out to be the ghost of a long-dead pirate who insists the Johnsons must leave. The ghost then asks the gang for their assistance in protecting his home from being abandoned.