I did Diploma for 2-years already now & am 24-years old. Am I eligible to pursue B.Sc in Viscom?

You have not specified about the college, where you wish to pursue the B.Sc Viscom course. However, the top college like Loyola College Chennai requires 10+2 in any stream. Hence, on the basis of 2 year Diploma your admission in B.Sc Viscom is not possible.

Yes, you can do any course.