The amount you got today (Jan 2019) as a check would not impact 2018 return, but might impact 2019 return.
The amount if very small. If this is a settlement due to you buying items from Family Dollar is might not be taxable income to you.
It might just reduce the cost of the items purchased there.
If this is result of the lawsuit where males were paid more than females, then " unless a portion of the judgment is for back pay or compensation — it is not taxable to the recipient" however if it for compensation it would be taxable income.
You will need to read over the details of the settlement.
