Lights Out ending explained

What happens

Trapped in the house at night, Rebecca finally gets her mother to see Diana for what she is. Sophie takes her own life, and Diana vanishes with her. The children survive and are left grieving, in the light.

The last image

Rebecca and Martin are left safe in the daylight, grieving their mother, with Diana gone.

What it says

The ending turns a monster story into a family tragedy. Diana was never separate from Sophie's illness, so only Sophie could end her. Her choice is a last act of love for her children, shown with sympathy, not blame.