So many posts. I can't read them all to find out if anyone suggested this.
Get her to write a journal of her deepest thoughts about the past, present, herself, you and her children. Paper preferably. To only be opened long after she's gone. There are things that a person will only say if they know that it will only be known long after their time.
Sometimes an oral historian can help to write it if the person can't write themselves.
Peace be upon you.