How does the narrator's mother react to to the grandmother?

The narrator's mother is a bit nervous and shy, but it isn't long before hugging her mother brings back the love and familiarity.

I did not see her, but I was alerted to her approach by my mother’s hand which suddenly tightened anxiously around mine...

“Child,” Da-duh said, and her tone, her quick scrutiny of my mother, the brief embrace in which they appeared to shy from each other rather than to touch, wiped out the fifteen years my mother had been away and restored the old relationship.