An Annuity is the safest investment possible (assuming no default risk from insurance company).
Who cares what it is making? All you care about is the cash payouts. Unless you have a fancy sort of annuity, the capital is not yours to touch anymore, in return for GUARANTEED payments, for life. Silver Bars are no where close to that level of guarantee.
A lot of people have this challenge with senior parents, but nothing you wrote indicates that she is unfit.
I think you need to talk to her, have her agree not to touch savings at all without talking to you, nor take out lease / mortgage or other loan, but let her spend out her monthly income.
You can work with her during the month as budgeting "crisis" arise, knowing that her money resets every month.
Also, see if the local community center has finance seminars (not sales) for seniors, our area does, and it is good advice given.