Two weeks in Nepal.....anyone need a travel buddy

I am going to be in Delhi for the first half of December with an animal shelter group. I want to stay extra and go to Nepal, but I will barely have 2 weeks there. Does anyone have any advice on the best way to enter Nepal via train or bus from Delhi? I need opinions on how to get there from Delhi on a tight BUDGET. Two weeks does not seem like enough time at all to see Nepal, so I would love some advice on the best places to hit up. I love to hike but I am not hard core. I am planning on being there from Dec 22 to Jan 5 if anyone needs a travel buddy.

The bus is pretty rugged but cheap. I've taken the direct bus a few times it takes 40 to 48 hours and only stops for a toilet break every few hours. It is an adventure in its own way. I actually had fun on the journey. You will see a lot of interesting things out the window! My son was 9 at the time and he loved the bus trip.The only bus company I can highly recommend is called ABC. A good friend has taken their buses many times and she too swears by them too. I think they go two or three times per week. I know you can buy tickets in Majnu ka Tilla the Tibetan area in North Delhi. Bring pain killers as it makes the ride a lot more enjoyable and bearable. It isn't really that bad but it is a long time to sit on a bus bouncing down the road!
Plenty to see and do in Kathmandu.