I think it was very clear that Big Edie had a Dependent personality disorder. Little Edie constantly brings up how her mother held her back in her happiness in life, forcing Little Edie to choose her mother instead of a husband, a career, etc. She wanted her to always be there for her.
shareLittle Edie clearly resented her mother for asking her to move back home to care for her. But...I do not believe that Big Edie had a dependence personality disorder. She was manipulative and emotionally abusive. She was also a selfish mother - but it was absolutely little Edie's choice to live with her mother is squalor.
Proof of this is the fact that both of Big Edie's other children were independent of her and extremely successful in life (family/socially, academically and professionally).