I agree, it is probably the best decision for Stella. I just hope Kia Walker is welcome to communicate and see her Granddaughter enough to feel recognized by Stella as family too. (Kia is even more actual family.) It'd be nice if Kia is encouraged to have a part in Stella's life in some way, given some time to be a part of her life.
She is her Grandmother, after all. She never quit trying to be part of Stella's life from the very start, and she deserves to have a relationship of some sort with her Granddaughter. Someday, Stella is going to be grown-up and wondering more about her father and that side of the family, and that link shouldn't be cut off. Just my own opinion.