India

You can improve your Class 12th marks of Kerala State Board through the National Institute of Open Schooling NIOS system by these few steps as per my knowledge firstly you enrol in the NIOS board for Class 12th examination. Choose the subjects that you want to appear for improvement. Study the syllabus thoroughly and prepare well for the exams and attempt the exams and score higher marks than your previous scores. Once you receive your improved marks from NIOS you can submit them to the concerned authorities of Kerala State Board. It's also important to note that the Kerala State Board may have its own rules and regulations for accepting the improved marks from NIOS so it's advisable to confirm the process with the relevant authorities of the board.

There are many top colleges in India for MCA (Master of Computer Applications). Some of the most reputed ones are:
National Institute of Technology (NITs), e. g. , NIT Trichy, Surathkal, Prayagraj, etc. Department of Computer Science, University of Hyderabad
Vellore Institute of Technology (VIT) Vellore
University of Delhi, Delhi
Jawaharlal Nehru University (JNU) Delhi
Department of Computer Science, University of Pune
Bharathiar University, Coimbatore
Christ University, Bangalore
University of Mumbai, Mumbai
Please note that this is not an exhaustive list, and there may be many other colleges in India that offer excellent MCA programs. It's important to research and compares different colleges based on factors such as course curriculum, faculty, infrastructure, placement opportunities, and overall reputation before making a decision.