She's faceless, as was the father, so I doubt she'll show up ever again.
To add to this, Aya has already moved on, she wouldn't want to meet her mother even if she could.
I liked the symbolism with the bell, it's sound was the first thing Koto and Erika noticed when Aya reappeared back in chapter 1. In a way, it was what let them find her, just like grandma intended. Considering she still has it on all the time, does she keep it because it remains something unchanging about her?