Too late now! Seriously, if you are retired and can’t afford to lose ANY money, then it belongs in a bank where these days you earn almost no interest! Anything else involves risk of loss.
Did you save in an IRA over the years, so you have something besides Social Security. If you have a significant amount of savings, then certainly you would want some stock market investments to generate growth over the long run, to offset inflation. But you didn’t say that, and I can’t speculate. If you can’t lose any money, leave it in the bank. One day interest rates will rise again.