The Ghost of the House

Malcolm thinks that Annie is the woman haunting the house, but Kitty doesn't. There could be more than one thing there and that may explain why they're having two different experiences. And then Nilo, we have this major incident in the guest bedroom. This is not just things dropping off a shelf. This is the entire contents of the bookcase spread across the whole room. Is it something that would be a natural outcome of some sort of shift in the ground underneath?