That answer doesn't make any sense to me, probably because the question isn't clear.  Is the $500 they owe, before or after the unemployment exclusion?  The amended return should include both the 1099-B income and the 1099-G exclusion.  If that results in a refund, file it that way and let IRS cross it off the list to change later.  (Also, might kill two birds with one stone if the state needs to be amended also. )