Each state has unclaimed property rules by which businesses must abide, and each state is getting more aggressive in enforcement (penalties for non-compliance). What this means is that after properties have reached the appropriate lapse period (1-3 years in most cases). The business needs to make a "due diligence" attempt in writing to contact the owner of the property, then if they can't located them they turn the property over to the state treasurer as unclaimed. If a person's name shows up on this list then they are to contact the Secretary of State in their state and claim it. If the person on this list is deceased, then the executor of the estate can do it on their behalf.
There are all kinds of unclaimed property -- safe deposit boxes, uncashed checks, deposits and gift certificates, real estate, stock certificates...
I would check with the Secretary of State in your state to make sure the claim is legit.