Dee's main reason for coming home isn't immediately revealed in the story. After she has been in her mother's house for a few hours, however, it becomes clear. She has come home to lay claim to some of her mother's possessions, to collect them and take them back to her home in the city. She wants her mother's old butter churn. Then she discovers the quilts. Dee wants the quilts, too, not for their sentimental value or their usefulness, but because she thinks they are valuable antiques and will look beautiful as decorations in her home. Dee cares little about her mother and her sister, she cares nothing about their feelings, and she cares nothing about her family heritage. Her coming home to take what she wants from her mother's house shows that she is vain, materialistic, and selfish.
Dee comes to visit to appropriate many of the handmade items that Mama and Maggie use every day. After years of finding her family embarrassingly backward, Dee regards the objects that her family uses as precious, likely because someone in her rarefied circles has told her that these items are priceless antiques. For example, Dee admires the benches they are sitting on, and then she covets the quilts that Mama and Maggie made from Dee's grandmother's clothes and that Mama promised to Maggie (Dee's sister). Dee protests that Maggie would put the quilts to everyday use, while she would hang them as pieces of art. It is clear that Dee is a selfish person who does not really care about how her mother and sister are doing. Instead, she thinks only about herself and has come to claim her family's few belongings because someone else has told her that the things she once looked down on are valuable.
Dee comes to visit because she promised her mom and sister that she would, she just vowed never to bring friends. What this says about her character is that she cares about her family, but she is embarassed by their heritage, and the way they live their lives.