The applicants are required to submit a duly filled in application form (same MRP application form), copy of passport and citizenship/Nabalig Parichaya Patra/ birth certificate, two recent color photo, a letter requesting for travel document, a money order of $ 40/- and a return envelope to send back the travel document.

Seems like they need photocopy of citizenship even for travel document. Your friend might have copies of his citizenship back in his home in Nepal. He can ask someone from his home email the copy of citizenship to him and then apply for travel document or MRP. If your friend is not planning to travel to Nepal, then he can apply for MRP with copy of the citizenship. It will just take lil bit more time than usual.