There were two stories I read right around 1980, books I checked out from my library, and I’ve never been able to find them in recent years. One or both of these stories may have been in a collection of stories, rather than a full kids’ or YA novel.One was a story about a boy whose family had moved into a house that had a big scary tree in the backyard. Each night the boy saw that the tree’s shadow crept closer and closer to his bedroom window. Finally in the end there was some conflict re a witch, and they chopped the tree down and filled the hole where the stump was with concrete.The other story was about a boy who loved next door to an old man, but it turned out the man was a vampire, and he trapped the boy in his basement, where there were coffins filled with dirt, I think. Suggestion: Apt Pupil By STephen King- the neighbor in question was an escaped Nazi war criminal, not a vampire, but the rest of it sounds close! Another suggestion: Prisoner of Vampires by Nancy Garden