I worked in a specific direction without communicating it to master's thesis advisor, problem?
It isn't a problem unless you make it a problem. I would think that what you have done shows initiative and would be praised normally. That should be true even if the committee suggests that you go in another direction for the thesis.
But, to me, at least, saying that you have been exploring one of the options seriously would be a point in your favor. But if other considerations are such that you should be taking another direction now, you can do that, and not insist that you follow up now on your current direction.
If they suggest a different direction, just put the recent work away for a while. You might have the opportunity to develop it further later and the experience of doing it might actually help in following up on the suggested direction.
As long as you don't fight with people, who might have good ideas as well as authority over you, then you should be fine. Maybe better than fine. Initiative is a good thing.
Likewise, a quick update to your supervisor on your recent activities should not be an issue as long as you are flexible.