[aopirose]

Maternal Grandmother – Died years before I was born so no nickname
Maternal Grandfather – Daddy

Paternal Grandmother - Grandmere
Paternal Grandfather – Grandpere

My son, and I assume my daughter will too, calls his grandparents:

Maternal Grandmother – Died just before my son was born but he talks to her picture and he calls her Granny.
Maternal Grandfather – Grandpa
Maternal Step-Grandmother - Grandma

Paternal Grandmother - Mimi
Paternal Grandfather – Papa

I have some older friends with a 2-year-old granddaughter. She calls them Honey and Bear. Another set of friends are called CoCo and Boompa.