My son is excellent in mathematics and science, so which stream should I suggest for him?

You can not assume that we know what you are talking about. "Mathematics" and "science" don't mean much, and the younger he is the less they mean. We have no idea what "stream" might mean. You have to explain your question well enough to suggest an answer.

If your son is in high school, I recommend you get him into an acting class with emphasis on any vocal skill. That will increase his earning power more than any other detail.