Stranger in the house

My family was going out to dinner one night. My sister was feeling sick, so she stayed home. Anyway, we were just getting in the car to drive home when my sister called my mom's cellphone. She siad that she heard footsteps coming up the stairs. My mom told her o get a blanket, a hanger, and hide in her closet incase it was a robber. She also said to keep the phone with her. We had to stop to get gas because the tank was empty, so we couldn't get home right away. We stayed on the phone with her the whole time. Suddenly, she said that something had just fallen, and it sounded heavy. There it was again! she screamed. As soon as we got home, my dad grabbed a hammer and went around the house searching. He said everything was safe, and we could go to bed. I went into my room and saw that all my trophies and medals had fallen off the shelves, and there were footprints (much larger then mine) clearly imprinted in the carpet. The scary thing was, we set the alarm to our windows and doors, and none of the alarms had gone off the whole night.