But ma'am in KEA website there are two kinds of paper Mathematics & computer science and MCA, for which paper I have to prepare for. 

Hi Vinod, You are confusing the papers. For M.Tech B category you have the Maths and Computer Science papers and preference. For MCA, you dont have a choice and they definitely wont ask to choose between Maths and Computer science. You just have one paper and will be tested in Mathematics, Computer Awareness, Analytical Ability and Logical Reasoning, General Awareness, General English. This is what is given as syllabus in the brochure - check page 21. And Check MCA 2016 question paper here and 2013 question paper here. Please check the past year question papers. They are given for some years at the PGCET 2017 website.