It might help you to clear the air in this friendship-for you! Depending on how she responds in the talk you have, and how she behaves moving forward, you can decide on the closeness level in the friendship.

I would be totally straightforward, but casual as you were at the group event(which btw, was completely appropriate what you said, bare minimum and truthful), but bring the conversation to a conclusion. Call her. Let her know “you know, you expressed that I should have called you” “do you remember how you distanced yourself from me in our friendship? I really cared about you and it felt lousy to be treated that way. I was hurt. I missed you. Then you insist that I be the one to maintain contact in the friendship.When my mother said you asked that I call I suppose I could have but decided that if our friendship is worth keeping, I shouldnt have to be the only one to make an effort.I felt that if I mattered enough to you, you would have made an effort to get my number. I suppose I could have called you one more time and said that then, but given your decision to distance me to begin with, I decided that I didnt want to be the one to make the effort again to have you not reciprocate by trying to contact me at times. Can you understand why I feel this way?”

If she apologizes and responds positively, then you will both come out better. If not, then you realize that she really lacks other empathy to the point that you should have very low expectations of her and a mutual caring friendship between you, and be grateful for the friends who really do care about you. I have met alot of people like this. We do ourselves or our friends no favor if we are the only ones making an effort in the friendship\.