Is this paranormal or just our imagination?

Hi! So i was at my friend's house and we saw a lot of things we thought might be paranormal. The lights flickering, things moving from place to place, being touched on shoulder, a spark under a chair, a face on the wall, and her treadmill went on by itself and changed speeds. She also felt as if she was pushed. We are considering that its just her dead *RIP* grandfather but we are so scared to go to her house!