Three months ago I heard 3 knocks on my door?

Three months ago I heard 3 knocks on my bedroom door and as i called out come in. I got up to check on my kids and they were all sound asleep. I questioned them the next day and none of them claims to have done it. So for a while i was spooked and then got over it. This past weekend my mother stayed over and slept in my daughters room,( she is with her father right now about an hour away) Friday night she slept peacefully in there but Sat. she fell into a deep sleep and was awakened around 3 am with somebody playing with my daughters things. My mother shrugged it off and went back to sleep. Again the noise got louder so being spooked my mother ran into my other daughters room and slept with her. As soon as she got into the room she heard a loud bang in my daughters closet as if something was chasing her out and trying to scare her. So she tried to wake up my daughter when my other daughter appeared at the doorway of her room. She was furious and wanted to know who was in her room and who was sleeping in her bed. She proceeded to argue with my daughter and she just kept saying noone and was just too out of it. Then my mother finally sat up in the bed and looked at her straight in the eyes and said noone ok look im sleeping with your sister, nobody used your blanket ! Then this image that was pretended to be my daughter called my mother a bit** and slammed the bedroom door shut to my other daughters room. My mother swears up and down that this happened and at this point she was certain it was my daughter. When she woke up in the morining and checked her room and she wasnt there. I called to check on my daughter and she claims she has not been home. She's only an hour away but i know my ex husband and he would not have taken her home at 3 or 4 in the morning. My question is has anybody else experienced this ? Should i be worried ? obviously this thing didn't want my mother in her room and ran her out. How should i handle this situation? Was this a demon?