That monster is known as the loving mother. its a deformed spirit that hunts down little boys and girls who are losing their innocence. by eating them with her genitalia, she tries to rebirth them as newborns so she can have a child to raise for her own, but the children obviously die in there so she digests them and finds another kid. they are thought to be the tormented souls of women who died during child birth and never got to hold their babies.