You don't have to do anything. Gifts that you receive are not taxable income. You do not report the gifts on your tax return.
If the gift to any one person had been more than $16,000 (in 2022) your mother-in-law would have to file a gift tax return (Form 709). But since she did not give more than $16,000 to any one person, she doesn't have to do anything either.
