If you plan in a right way, and take train for traveling, you can visit "Dehradun, Rishikesh, Haridwar"; "Jammu and Vaishno Devi trip"; and "Shimla" for 3 days.
I'd travelled all these three localities with 4 members of my family in just 20-25k for each trip.
Hey there, you can go for Shillong and Kaziranga National Park, according to the conditions you have mentioned. You will be able to witness the 7 sisters waterfalls if you visit now or within a month.