This is the answer.
For many people who don't understand technology, the solution isn't more technology. Is a password notebook technically less secure? Yes. But it's much better and more understandable than what she really wants, which is the same username and password for everything.
Plus, a notebook is great way to pass information that's not just usernames and password. It's in invaluable resource in case of death. Digital is great, but physical copies are important.