Depends on what state college you are going to... there is a huge difference from say, UCI, and UCLA. But in your situation, I would actually choose 'B.'
"A' is not a desirable choice as even with the slight increase in average salary, it could take you maybe 5-6 years just to break even, assuming you do get a job that is higher paying immediately after you graduate from Harvard. With each passing year, an MBA becomes more and more useless as the market is already flooded with people who have MBAs, even from top tier schools. Especially during this recession, everyone and their dad left work to get an MBA.
I'd say keey your job now, save up, invest, and enjoy the returns later. 15k is a small investment on the side for an MBA that might be useful later.