The story has multiple first-person narrators. Each of the main characters and some of the minor characters tell the story from his or her perspective at different points in the narrative. The reader gets the thoughts and feelings of many of the characters in the story rather than just one of the characters. As a result, the story is about the whole family instead of just Rufus or Mary.
When deciding what the point of view is in a story, pay attention to the pronouns used in the story. "I" or "me" would indicate that it is first person. "She" or "he" indicates third person. When the reader knows what just one of the characters is thinking, the point of view is third-person limited. When more than one of the character's thoughts and feelings are given, this is third-person omniscient.