Picture Mommy Dead(1966)

Susan Shelley is released from an asylum where she's been confined to after the shock suffered over the fiery death of her mother. Her father has a new wife, who has only married him for the money left to him by his dead wife. Susan is still haunted by her mother's memory, and her step-mother is conspiring with her lover to get the troubled girl to lead them to her mother's missing diamond necklace.