You can take the package of Kasol Kheerganga trip. You can stay at cheap tents in kasol. Check out the packages from Tripoto at -
https://www.tripoto.com/tour-packages
The best package you can surprise them with is the spiti valley round trip package.. but I guess it's going to be expensive.. Kashmir, Shimla, Manali packages are relatively cheap
Hi Piyush You should gift them Kashmir or Kerela tour packages. There are cheap as well as expensive packages. You can choose from them. Check on tripoto.
I prefer you the place GOKHARNA it is place of Beaches and hills stations. Both will be covered for you in this place. It is located in Karnataka, India.