Can you help my friend out. She is going nuts trying to remember this book.

Can you help my friend out. She is going nuts trying to remember this book.

Okay book loving people! I recently read a book and I can’t for the life of me figure out the title. I only know a few details about what happened in the book, but not entirely sure if I am correct lol It has been bugging me for about a week now! Here it goes...

In the book, I remember a girl going to her grandmothers house by a lake or ocean and she unveils secrets by reading through her journals. She comes across a number that she calls and it’s a grandson to her lover 🤷🏻‍♀️ I think. She then goes and visits someone at the nursing home to ask about the secrets about her grandmother. I know this is VERY VAGUE, but that is all I remember. 🤪🙄