Whats the name of this movie?

all i remember is that its about sum cave hikers. they run into like mutants who cant go in light or something. they try to fight em off but they die. in the end theres like 2 survivors. 1 betrays the other to escape so the mutants come after her. when the last survivor escapes and is in the car her friend (the one she betrayed is in the backseat waiting). they were on vacation or something. whats this movie called??