This was a lifetime movie from around 2013 or 2014. Two children, a teenage girl and her younger brother, had their parents die. So they went to live with their maternal aunt and her husband. Around the neighborhood people were going missing. As it turns out the woman and her husband were homicidal killers. They even killed the girls parents. During the final showdown in the basement, the aunt corners the girl and is about ready to kill her with a knife, but then the brother kills the aunt. Any ideas?