Best thing would be to discuss this with your thesis advisor or a professor at your university. Also, review the existing literature. The google scholar and microsoft academic search engines are excellent for that, so are the librarians at your university.

Spend a few days or weeks reading up on the existing academic literature in the area you are interested in, and see if you can identify a hole in the research, something that hasn't yet been done. Then speak with your thesis advisor or a professor and revise it until you get a research question that you can, in a masters dissertation, answer sufficiently.