"Emily never sees the light because she's been in hell." - Anonymous / by H.P. Mendoza

At the end when she says "There is no light!" it's because suicide is a deadly sin, worse than murder. When she killed herself, she didn't just die, but she went to hell, forced to repeat her struggle over and over. When the movie is over, Sylvia is trying to move her into the light, but Emily moves into blackness. You can start the movie over again and realize that she has been in hell the whole time.