Charlotte is the nurse, not the little girl. Girl's name was Mandy Phillips. Nurse Charlotte harmed the children (breaking their legs, arms, etc.), so that they would stay near her because she "loved" them ("1959"). Her ghost is still scaring the children that are now in the hospital which is about to get closed ("present-day"). Charlotte's ghost is harming the children again, because she is afraid that children will leave her. Nurse Susan, Roy and little girl Maggie die and many are harmed (nurse Amy too), but they managed to escape from the hospital alive.