Hi priyanka, I recommend you to go for Bunkstay in Rishikesh, which is at the backside of Laxman Jhula.
Its awesome and you will get relax,awesome view, bikes on rent and complimentary breakfast. Also book directly on reception over there, because booking through BOOKING.com will cost you same (without breakfast) You can check good hotels near mall road and market area in Dehradun and Rishikesh through Booking.com.
I will cost you around 1.2k per day in budget .
Go to booking.com and search for hostels .. In Rishikesh I would strongly recommend Zostel Rishikesh , it's in amazing location . The view from rooftop reaturent is just great and the rooms are so clean and super pocket friendly ..