Company Secretaryship

Yes, you will be eligible for fashion designing. For information related to SET 2018, check out the exam page below:
https://www.shiksha.com/b-tech/exams/set

I am also a computer science executive student, and I am also planning to do MBA in 2018, because we are not getting results as we are hoping.

Please refer to the link provided below for an exhaustive list of colleges which offer M.Sc. courses in game design in India. You should be able to navigate to a college of your choice using the filters on the web page.
Additionally you can also download the college brochures which contains important information like course eligibility, fee structures, placements, reviews and rankings.
https://www.shiksha.com/it-software/game-design/colleges/colleges-india

With PCB, you can't opt for B.Tech/BE computer science as for B.Tech you need to have PCM as mandatory subjects but you can surely become a programmer by opting for courses like BCA, B.Sc IT, etc. Degree along with sound technical skills will help you in achieving your goal.

CS and LLB is a great combination altogether as in case of corporate law you can easily enter into the capital market and company as in most of the places have legal and secretarial department as a singular entity.