My kids called my mum Ma, dad's mum is Grandma, my sister's MIL (who we see heaps) is Granny Shel
My stepmother had a grandma from Ireland, and the whole family calls her "herself". I thought that was kind of neat, if a bit fancy. I called my paternal grandma Mem (short for memere), and my Maternal grandma Gram.
My girlfriend has her grandson call her G-Mama. I laughed so hard when I heard that. My little one calls my mother Mom-mom.
I called my grandmother Granny and my daughter calls my mother Gigi.
My daughter calls my mom , mom and she calls me mommy
Memaw, maw maw, Mimi, ya ya, ninny (what my mom is called), gamma, nanny, nanna, there are tons