The answer is B. Millie and Vanessa live two blocks from one another.
Writing in third person is writing from the third-person point of view, or outsider looking in, and uses pronouns like he, she, it, or they. It differs from the first person, which uses pronouns such as I and me, and from the second person, which uses pronouns such as you and yours.
Writing in the third-person provides flexibility and objectivity. In fiction writing it enables the narrator to be all-knowing. The personal pronouns used in third-person writing are he, she, it, they, him, her, them, his, her, hers, its, their, and theirs.
Hoped I helped!