Hello Sruthi.

Congratulations on securing this rank.

Before applying to a college, I would suggest you to go through the first year syallabus of the college. If you have studied those topics before and are well versed with them, you can opt for lateral entry. Else, you should undoubtedly apply for the 3 year MCA course. 

Lateral entry on one side will reduce the one year from the three years and correspondingly the fees, but the problem will arise when you will have to prepare for campusing in the third year, where you will also need to study the basics that will be taught in the first year, which you will miss. This in return will hamper your chances of gaining in depth knowledge, which can create problems during exams and interviews.

Now the choice is yours.

Hope that helped.