The term "selfish motherhood" is really an absurdity. Motherhood in fact counters selfishness. We have that great example of all mothers: Mary. We have, by God's providence, the example of our own mothers who by and large always turned to Mary for help. May we ever grow in our appreciation and love for each of our mothers, living and deceased, and for our Blessed Mother.
We might note that the apostrophe occurs before the s and not after the s in Mothers Day. The reason is that this day is specifically for each mother and not as a collective whole. Its a reminder that each of us should be thankful for and value our own mother personally. If we are fortunate to have her alive with us, then we must show our love and respect for her by our deeds and words. If she has passed on, then we should always remember to pray for her and to thank God for the gift to us that she was.