We can only speculate as to why Emily is so reluctant to let go of her father's body. Except for the old servant Tobe, Emily and her father lived alone in the big house for many years. The narrator tells us that Mr. Grierson thought no man was good enough for his daughter, so she must have been more or less a recluse or socialized only with her father's friends when she was younger. When he died, her whole reason for being collapsed. Without her father, she had no frame of reference, no way of relating to people as herself. She would not admit that he was dead and for three days refused to let people into the house. The narrator says that she met people "at the door, dressed as usual and with no trace of grief on her face." It was only after she "broke down" that anyone was able to remove the body and quickly bury it. When she recovered from her breakdown, she had a completely different appearance, with her hair cut short. The narrator says it made her look young. Since her old life had passed away with her father, she had to begin a new life on her own.
Miss Emily does not actually keep the dead body of her father. It is, rather, the body of Homer Barron, the man with whom she had a romantic relationship. The narrator hints that Emily poisoned Homer, who would not marry her, but Faulkner leaves the question about why she keeps the body open. One possibility is that she wanted to spend her life with him and realized the only way he would allow that is if he was dead! Many motives are suggested but none are confirmed. Miss Emily's sanity is questioned, as well as the nature of the relationship she had with her overprotective father.