Who is the antagonist in Everyday Use by Alice Walker?

That would be Dee. Dee is the source of stress and anxiety in the story. She returns home to culturally appropriate her past. As it happens Mama and Maggie still use the items that Dee thinks are quaint. Mama finally stands up to Dee who leaves in a huff. Once Dee is gone, the anxiety is abated and Mama and Maggie can be themselves.