Hard Rock Nightmare (1988)

A young boy named John is tormented by his grandfather concerning vampires and werewolves, until he believes his grandfather is actually a vampire. This of course, leads to John killing his grandfather with a stake. Fast-forward and John is now the lead singer of a rock band who can no longer practice in their garage so they're forced to a house in the middle of nowhere, left to John by his Grandmother. They soon begin to be picked off and Josh is convinced the stories his grandfather told him all those years ago may be true.