Diane Kaplan, 64, of Hamden,  died May 14.  She was the wife of Stephen Mayer. Born in Minneapolis, Minn., she was the daughter of the late Harold and Ruth (Berman) Kaplan. In addition to her husband, she is survived by her children, Hans Kaplan Mayer of Belmont, Mass. and Irina Kaplan Mayer of Ludlow, Vt., She was also predeceased by her sister, Susan Kaplan.