You can ask any expert /CA to file your NIL returns. ITR does not mean that you should have any income. charges will be less than Rs.500. Inbox me if you need any more details.
Paying income tax doesn't mean you earn more or less, hire any regular CA he will file income tax for you might charge max 2000/-
Make a covering letter, write very specifically and self-explaining that who is paying for this trip, attach that person bank statement, your bank statement confirmed hotel booking, confirmed air ticket return, travel medical insurance for, attach your accommodation letter along with your application and wrote about it in your covering letter. Your Adhar card, pan number, if you doing a job, your company letterhead, stating your job profile designation and salary. Duly stamped by your HR, leave application. Copy of credit card if any, fixed deposits if any, insurance if any, property papers if any. Membership of any club or sports club, if any, and last if there is any travel history.
Good Luck!!