Hello aspirant
Yes you have to submit gap year affidavit to your respective college. All college need gap affidavits if applicable. You can get a gap affidavits by contacting with a lawyer ,on a 20 rs notery they will print your reason for gap year signed by concerned authority that will hardly cost you 200 - 300 rupees.

You need to submit that affidavit as your gap year certificate.

Hope this will help

Best of luck.