Personally, I have an investment grade corporate bond portfolio with a coupon rate of over 7% ... average maturity of 18 years. But that's me, and not my parents .... Nope!
I have them in online brokerage offered CDs (from name banks) that pay more than treasury bills and aren't short term .... 3-5 years. I opt for Call Protected ones (less yield) and rates have come down a bit.
Current rates on Fidelity offerings ... CP.
3 years 4.6%
5 years 4.3%
Same FDIC protections and a sure thing ... and liquid.
As rates come down, the price on my corporate bonds and these CDs will increase ... and liquid.
Check them out for your mom.... shorter durations will beat treasuries usually and offer higher rates, but I don't want short term stuff ....
And rates will fall within a few months for treasuries, CDs, money markets, and online savings ... what then?
You'll wish you had "locked in" in 2 or 3 or 5 years imo. Build a "ladder" mebbe...???
This advice is worth .03 .... inflation adjusted