I would recommend them to invest money in a ''Time-deposit Account''. A time deposit account is not insured by the FDIC and in case a bank goes bankrupt, FDIC does not guarantee to give you your money deposited in the time-deposit account. A time-deposit account provides a fixed interest rate on the deposited amount on the principle.
Another advantage of a time deposit account is that the Joneses could easily withdraw some money in case of an emergency, however, if they withdraw money before the maturity, then they would not be able to earn the interest. This is a highly liquid and safe investment with a fixed interest payment.
There are many different variations of a time-deposit and different banks provides different flexibility and minimum deposit requirements in order to differentiate their product offerings.