The refusal of the mother giving the quilts away to Dee makes a big permanent change in character.  The mother has not done anything like that before because it is Maggie's wedding present.  The mother is also use to giving things to Dee because Dee she is so selfish.  The mother did it now because it was made by Maggie and her.  She was also tired of Dee being so selfish all of the time.  The details in the story that indicate that that was coming is that the mother already chose to give it to Maggie and that Dee's words did not change her mind at all.  Also why would the mother give away Maggie's wedding present to Dee instead of her.