A gift received from an individual is not reported on tax return, regardless of the amount received.
Since the parents are US citizens they are required to complete a Gift tax return, Form 709, for any amount given to a single individual over $14,000. Unless they have made over $5.43 million in gifts over the years, there will be no gift taxes owed.
IRS Form 709 - https://www.irs.gov/pub/irs-pdf/f709.pdf
IRS Form 709 instructions - https://www.irs.gov/pub/irs-pdf/i709.pdf
