According to Eileen Heckart's son's biography of his mother, De Havilland, Ingrid Bergman, and Angela Lansbury were all serious candidates for this role. But in the end Eileen Heckart reprised her stage role and won an Oscar for it.
Lansbury (along with Ingrid Bergman and Olivia de Havilland) was one of the three major contenders for this role, but in the end Eileen Heckart repeated her stage success and won an Oscar.