Finding out that your darling baby grandchild is deaf is certainly 
tough. The parents are most likely in turmoil. You probably are as well, and in addition, your family needs you to be strong, whether or not strong is what you feel.
An Australian organization that helps children with hearing loss had some advice that seemed like it could come in handy in lots of hard situations. You might call it the support stance, with caveats.
A woman identified as Grandma Carol offered this: “We are the support, the shoulder to cry on, the ones to be grumped at when things go bad and understand the reason for it and not get angry. We are the backstop to take the baby and give Mum a break. We are the font of all knowledge, and know nothing at all. We are the ones who give unconditional love to our beautiful grandchildren and walk with pride as we wheel them in the supermarket with the hearing aids and processors, and answer the questions from other children, and well meaning stupid adults.”
The upshot for Grandma Carol: She went back to school, and became a teacher of the deaf. “I have amazed myself…..I am loving every minute of it.”