All businesses depend on the quality of their strategies. Family businesses are no exception. However, strategies address the appropriate use of the tools provided by other functions. Taking only strategy courses, especially in a small or family business where there are unlikely to be several functional experts on staff, would be counterproductive. That doesn't mean you shouldn't focus on strategy, simply that you should be sure to gain basic competence in all the managerial skills taught in B-school.
Many people with strategy backgrounds go into consulting, but large corporations also have strategic planning departments. There are many resources on strategy including even a "Dummies" series book. Keep in mind that planning in a family or small business may, of necessity, be more involved with the details of specific functions, making a broad background more important. Try checking out some of the better journals such as the Harvard Business Review.
https://hbr.org/search/Strategy
Good luck,
