Helping to write memoirs for my 90 year old grandmother

My grandmother has her 90th birthday later this month and I would like to buy her the gift of someone helping to write her memoirs. She has been talking about wanting to this over the last couple of years and has started writing some stories.

I am looking for someone to help put the stories together in some sort of order and what I would like at the end would be to have a book made with some pictures - I am looking into services to produce the book so at the moment, the job that I am looking for is help in writing the book.

It would be good to understand how many hours this would be projected to take to get a quote, to see if this can be done within my overall budget.

I should have added that I imagine there will be some zoom calls needed to help extract the stories and develop them.