Lauren...
In a situation like that where there's a killer inside or outside the house, and that there are dead bodies outside, wouldn't it have occurred to them to wake her up. When Kelli and Leigh went downstairs to see if Ms. Mac and Heather are alright, Leigh told Melissa to stay with her friend, but basically Melissa stayed alone. She was attacked and no one was around to help. If I was them I would have woken her ass up, get her dressed and tell her what the hell is going on!
I hate it when people split up in horror movies.