For this case what we should do is to choose the correct reflexive pronoun for the sentence.
In Spanish of Spain, reflexive pronouns are given by:
Yo ----- me
Tú ----- te
ÉL/Ella/Usted ---- se
Nosotros --- nos
Vosotros --- os
Ellos / Ellas / Ustedes --- se
Therefore, for the next sentence, the correct reflexive pronoun is:
Mi hermana me da la llave a mí.
Answer:
Mi hermana me da la llave a mí.