I am afraid that it will be difficult for you to be selected for MCA of any prestigious university unless you qualify the entrance test set for MCA course. Normally all the reputed universities conduct both written and oral tests to screen out the deserving aspirants for the said course. The written test comprises Mathematics taught at 10+2 level, English and Aptitude Test and unless you qualify this test, you will not be allowed for the oral test being conducted by the members of the Board.
Mathematics is the essential tool helping you to understand the complexities of computer domain. It consists of different sections such as Algebra, Trigonometry, Calculus, Vector Algebra, Differential Equations, Matrices etc which will help in understanding the basics of different tools of computers.
In your case, you have not gone through Mathematics at 10+2 stage nor was it covered in your B.Com stage though Accountancy was one of your papers which in no way will provide you basics of Mathematics to be employed in learning the computer skills during your MCA session.
If you are determined to fare well in the Mathematics included in the entrance test where you will be tested for your skills in Mathematics, English and Aptitude Test, you need to achieve expertise in this subject either through the professor teaching Mathematics in a college or from a subject expert of this subject teaching the aspirants for the Engineering Entrance Test. In that way, you can perform brilliantly in the test set for MCA.