The correct option is C she/that/her
The first blank requires as its subject a third person singular feminine subject pronoun, "she". The second blank requires a relative pronoun to introduce the second clause"..mother lives in a farmhouse". "Which" cannot be used as it does not refer to persons. The third blank requires a third person feminine singular possessive pronoun in the subjective sense to indicate the relation of mother to the daughter, hence, "her". Hence, Option C is correct. The rest of the options do not adhere to this rule, hence incorrect.