Right answer:
b. volvimos
Luego, nosotras volvimos a la casa de Ángela.
volvimos is the conjugation of the irregular verb volver for the first-person plural in the preterite tense. The preterite tense is one of two simple past tenses. We use this to point out actions that took place or were completed at a certain point in the past. So the this sentence translates into:
Then, we went back to Angela's house.
