Hi Heather!
I agree with Janet in that the best and most loving thing you can do is communicate with your M. about this. Ask her why she rarely (or never if it truly is, but don't use that word if it's not) initiates calling you. You can gain some insight into your M. and have a better understanding of her. You can also share with her that you would like her to call sometimes and share with her why that is important to you. Most people will respond when we share with them something they can do that would make us feel loved.
Many women (myself included) have a couple of terrible communication habits that we need to work on breaking. The first is that we try to read people and draw conclusions about their motives without communicating directly with them and getting the answers from them. This sets us up for wrong interpretations, wrong responses to wrong interpretations and then hurt feelings and a strained relationship. Gentle, yet straightforward, communication would clear up alot of that.
We also can expect people to know what we want/need without telling them. To us it seems "obvious," but in many cases it is not. We can respond with grace and love by not expecting someone to read our mind and communicate with them directly about what we need.
I do not want to sound harsh and hope that I didn't because I struggle with doing the same things in my communication and have to battle it constantly. I encourage you to not ask other women if their moms call or not and why that might be, and to talk to your M. directly and get the answer from her. I hope this helps a strained area of relationship with your M.!
Love in Christ,
Lisa :)