I would like to know the name of a horror movie I saw a few years back.?

In this movie a group of people go on the road possibly trying to evade police because they're carrying some sort of drug ( possibly cocaine) and they need somewhere to stay the night so they make a stop at a sort of house/motel. The family that lives in the house turns out to want to kill them in order to feed themselves and their mutant children. But since one of the girls of the group is pregnant the family decides to spare her and marry her to one of their family members. One guy that actually gets to go underground films his encounter with the mutant children and survives only to get killed in a sort of heat chamber. The movie ends by the pregnant girl biting a piece of a woman's neck off and escaping to later be captured by the police.