The little girl... (spoilers)

Did it make anyone else angry that they made the little girl do that in the end? First, I didn't understand why she was back in the place after she's escaped to the outside when the guy grabbed the main character woman (Julie Benz's character). Unless the cop brought her in. If I were her I would have refused to go back in the place.

Then at the end when they ask her if she wants to join them, and she smiles, I think, OK, so I supposed she could have just been playing along so they wouldn't kill her. She did act scared when she was trying to escape with Benz's character. But was that an act? Because she didn't act that bothered by what was going on throughout, when she knew all about it. She said sometime near the beginning or middle something like, "You don't want to get evicted." But she was always sneaking around and didn't really seem to want to help the woman or be that upset by her being killed in the end.

Just weird. I thought this movie was sickening.