One idea could be a family moves into an old, dilapidated house. At night, they hear strange scratching noises coming from the walls. The children start seeing shadowy figures in their rooms. As they investigate, they find a hidden cellar filled with old, creepy dolls that seem to move on their own.
In the haunted house story, the house was once an asylum. The main character starts to experience hallucinations of the former patients. There are cold spots throughout the house, and doors slam shut by themselves. The character discovers old patient records that reveal a dark secret about the asylum's doctor, and it seems the doctor's spirit still haunts the place. The character is constantly tormented by the doctor's apparition until they figure out a way to put the spirit to rest.