Essentially, you have a short-term loan to your parents coupled with a gift of $50,000.
You might want to seek professional tax guidance for this transaction as well as local legal counsel.
In short, there should be documentation concerning the loan and the applicable federal interest rate (AFR) should be charged on the outstanding balance.
See https://apps.irs.gov/app/picklist/list/federalRates.html
Further, a gift tax return (Form 709) will have to be filed for the $50,000 gift since it exceeds the annual exclusion ($15,000 allowed to each of your parents - total of $30,000).
See https://www.irs.gov/instructions/i709#idm140535812766672
