Final answer:
The correct verb form to complete the sentence is 'volvimos'.
Step-by-step explanation:
The correct verb form to complete the sentence about Sonia's New Year's Eve is volvimos.
The subject 'nosotras' is the first person plural form of the pronoun 'nosotros', which means 'we' in English. Since the verb needs to agree with the subject, we use the form 'volvimos', which is the first person plural form of the verb 'volver' meaning 'to return'.
Example: Luego, nosotras volvimos a la casa de Ángela. (Translation: Later, we returned to Angela's house.)
Learn more about Verb forms in Spanish