How does Mama change at the story's climax, and what is the meaning of that change?

At the end of the story, Mama has made an important realization.  In other words, she has had an epiphany.  This moment occurs when she takes the quilts from Dee and returns them to Maggie. 

Dee tried to take the quilts that Mama had given to Maggie; Dee wanted to hang them to show them off in her home in the city.  Mama, though, knows that understanding their family's heritage involved using the things that had been passed down from generation to generation; plus, she knew how badly Maggie would be hurt if Dee took the quilts. Mama decides that she will not let this happen, so she snatches the quilts away from Dee.  

Mama realized that she no longer felt controlled by Dee.  She was now free from that and could feel content in knowing that she had done what was necessary to do so.