The owner and a former employee of the now-defunct Nita Nita have teamed up for a much more upscale and delicious effort in Stuyvesant Heights called Mama Fox. Photo: Mama Fox The closing of Nita Nita was mourned like few other bars in Williamsburg when it shuttered two years ago, after losing its lease to a greedy landlord. Beloved by its regulars, the trusted standby stayed true to its neighborhood bar DNA even after the neighborhood lost its identity. But owner Samantha DiStefano wouldn’t stay down for long. This month she opened Mama Fox in a landmarked building in Bed-Stuy, home to the former McDonald’s Dining Room. Together with former Nita Nita employee turned Miami-based chef Francisco Anton, the new bar and restaurant offers …