The correct option is A her
The forms him, her and them are used when a pronoun is the object of a sentence. The forms his, her, hers, their and theirs are possessive in nature. Possessives are of two kinds: possessive pronouns and possessive adjectives. Possessive adjectives go before nouns. Possessive pronouns are used alone. Possessive pronoun and possessive adjective form ofheis the same, his and of she is her. Its is the same thing only when gender is not present.Theirs is a pronoun used to refer to a group of people who are in a group. The sentence over here is used for a "she". Thus, option A is correct.