I'd try to get her to buy an annuity or some other way of putting the lump sum out of reach in exchange for a fixed revenue stream -- maybe justify it as a tax

I'd try to get her to buy an annuity or some other way of putting the lump sum out of reach in exchange for a fixed revenue stream -- maybe justify it as a tax thing, or what if she lives ~30 more years due to great new medical science, and then convince her to put a credit hold on her own account (to prevent loans).