Answer
The movie featuring Mara Wilson as Natalie Hillard is Mrs. Doubtfire, a heartwarming family comedy released in 1993. The film follows the tale of a loving father who, after losing custody of his children, disguises himself as a nanny to remain a part of their lives. Mara Wilson portrays one of the children, Natalie, who forms a special bond with the nanny, unaware that it's her father behind the disguise.