Reading other answers I gathered that Manipal is a great place for CSE, while I know that Xavier’s is excellent for economics.
What subject do you want to study? Think of ten years down the lane. Do you want to introduce yourself as “I have studied Economics” or as “I am a computer science engineer”? What do you want to become? Do you want to study higher and research or take up a job? If you want job then what kind? Are you fine being a software engineer (for example) in an MNC or do you want to be a business consultant? In both cases, what kind of outlook do you want? If you want do to research, then what are your interests? Which kind of discoveries, theories and inventions attract you more? Does Shannon’s Information Theory influence you more or is it the Game theory which inspires you more. The idea is to delve more upon both of these subjects and select one.
Well, there are domains where the two subjects meet also. And there are fields in which expertise and understanding of both will be required. But there are many many different directions in both these fields. They are two vast worlds. Chose which you would like the most. It is not easy but it is a critical decision for your future.