Joyce Caulder was Tamara Caulder's mother.
History
The Caulders weren't very rich, and learning their daughter Tamara was "special" proved even tougher. When a representative from the Academy for Arts and Sciences approached them with a proposal to enroll their daughter into a special school, they were very happy for her, hoping she would make it. However, after Tamara was gone, Joyce discovered she left her favorite toy behind. When Harry called the numbers of the institute, he heard no response. Worried, he filed his daughter missing.
Soon after, Batman stopped the Brain Trust's operations. Tamara was reunited with her parents. They were taken into a witness protection plan.