Skull Ghost

The film

After the death of Shaggy's Uncle Beaureguard, he, Scooby and Scrappy arrive at the late uncle's Southern plantation to collect the inheritance. But as soon as they arrive, they find it is haunted by the ghost of a Confederate soldier. With this spook on their tails while they solve riddles in search of the inheritance, they seek help from the Boo Brothers, a trio of ghost-exterminators to help catch this nasty ghoul.

Synopsis from TMDB.