Idea #3

Kid is hiding in a closet, being shaken by an unknown person,
He wakes up early sneaks back to his room. At breakfast his mother asks if he's been having nightmares again, he denies that it is nightmares.

That night the same thing happens and we see someone but only their feet and witness them chasing him until he hides in the closet and they stop abruptly outside. The door rattles and shakes again until everything falls silent. It is silent for a long time until there are three loud knocks on the door. He approaches it carefully yet it only his mother who carries him back to bed. They pass a door that has a girls name on the outside of it.
We see him unable to concentrate at school and as he walks to the gate outside his house he passes a lamppost outside with flowers tied to the side.

Once again that night he is chased downstairs by someone yet this time we see the person and it is a teenage girl, we hear her shout at the closet telling him to open it, he shouts back telling her he is confused and frightened  and to leave him alone. This quietens her and the thinks for a while, she address's him properly and says that she is sorry for scaring him so much and that she loves him. She then places her hand on the closet and tells him that she only wanted to say goodbye. He hesitantly stands and places his hand on the other side of the closet door opposite to hers. He opens the door slowly but there is no one there. He rushes to the other rooms but still finds no one. He turns to look on the mantlepeice where there is a picture of the girl.The same picture is stuck to the lamppost outside with the flowers. She was his sister. It ends with the boy sleeping peacefully in his bed with a nightlight, this switches off as the scene turns to black.