Agnes Varis, a prominent patron and board member of the Metropolitan Opera, has donated $250,000 to Opera Orchestra of New York, the company said Monday. The money will go toward a concert performance of Meyerbeer’s “Africaine” at Avery Fisher Hall on March 2. Eve Queler, who founded Opera Orchestra in 1967, will conduct. The organization is trying to make a comeback after having suspended opera performances for several years because of financial problems.