This is the more logical answer. This sentence uses the reflexive pronoun se for the third person plural. Reflexive Pronouns is used with a verb to point out that a person carries out an action to or for himself or herself. On the other hand, visten comes from the verb vestir and maquillan comes from the verb maquillar. Both conjugations stands for the third person plural as well. Finally, we can write this sentence as follows:
Ana y Marta se visten muy elegantes y se maquillan para ir a la fiesta.
