The Hand that Rocks the Cradle (1992)

Peyton Flanders (Rebecca De Mornay) seemed to be the perfect nanny, but secretly she was out to wreck the lives of the family she was supposed to be helping. Before becoming the nanny, Peyton had a miscarriage due to the stress caused by the death of her husband, Dr. Victor Mott (John de Lancie), and blamed it on Claire (the mother, played by Annabella Sciorra),. Claire suspects nothing, having never met Peyton before.