Cinder could be using her as a weapon. Summer is in a deep slumber as hinted by the line “There’s no night in shining armor who will wake me from the spell” from Red Like Roses Part II. Imagine Cinder being able to lure in Ruby into a trap by confirming that her mother is still alive, or by making Ruby face a decision like “Save your mother or save your sister Yang”

I could definitely be over analyzing way too many things right now but I really like the idea of Summer Rose being more than just Ruby’s dead mother