I want to go USA for my higher education. So, which test is best for me IELTS or Duolingo?And if you don't mind can you share with me University list of USA for masters in computer science program?

Both IELTS and Duolingo are accepted in the USA. While Duolingo is an equally valued and recognized English proficiency test, the most widely accepted test is still the IELTS. So I would suggest you going ahead with IELTS. 

To pursue an MS in Computer Science in USA, you can consider the following universities:
Stanford University

Harvard University

California Institute of Technology

University of California-Berkeley

Massachusetts Institute of Technology

The average tuition fees for studying an MS in Computer Science in the USA for a Private University is $35,000 (INR 26,00,00)/ year and Government University is $30,000 (INR 22,50,000)/ year

You can also consider the following scholarships for doing an MS in computer science if the expense is a bit too much: 

Tata Scholarship

Fullbright Scholarships 

Chevron Scholarship 

Let me know if you need any more information or assistance from my end for your application.