Wow, what a can of worms, couldn't she just have found an Indian one ? Firstly, you say the V5 will be in her name, but surely it will have to go back to DVLC first, which begs the question was it SWORNED or not, if not then back tax will be due in UK. If the bike was registered with Nepali customs when it entered Nepal, ie it was stamped in on the CDP, then they have a record of it entering and it should have been surrendered to Nepali customs as soon as the CDP expired, there will also be the matter of outstanding Nepali roadtax @ 108 Nrps a day. Unfortunately, even if you can get a new CDP, it doesn't really help you, as getting a Nepali import stamp put in it is only half the problem, as you cannot enter Nepal without exiting India. So, first you must enter India, then you can leave India and enter Nepal and then you can leave Nepal and re-enter India, of course, in order to discharge your CDP and return your deposit, you will then need to leave India again and ride the bike back to UK, as that is the bikes country of registration.
Personally, I would say you have 2 options
1) ride the bike around Nepal and then sell it on............
2) The Nepali/India borders close at night, you could ride the bike through after dark (Saunali is a good post for this as there is not much of a barricade ) Stay at the uptdc 200mtrs down the road and walk back through to Nepal in the morning to get your passport stamped.
Of course, you are now riding a completely illegal bike in India, but you are already doing that in Nepal anyway !
In my experience, you will be very unlikely to be stopped or bothered by police in India and a few Rps will usually sort them out.
Good luck !