Just Sold Their Home

It no longer matters to the IRS whether you buy a replacement residence or not.  I'm surprised that someone your age even remembers that old tax provision, which hasn't been in force for at least ten years.
These days the homesellers tax break applies to sellers of any age.  If you owned the house and occupied it as your main residence for at last two of the past five years, as a married couple you can take a profit of up to half a million dollars on the sale with no federal capital gains tax due at all.  You could even do it again on another house in the future, as often as every two years.