Give Spy Holodisk to authority in NCR

Go where Darion is and scan the computer right behind him. Get the holodisk to Vault City. Before you are able to give the holodisk to Lynette you must have wiped out the raiders, this way you'll be able to get a book inside the black vault (a real vault, not a vault-tec one) and then give her the book, so you may show her the holodisk.