Her mother, Australian opera singer Clytie Hine, studied at the Elder Conservatorium of Music in Adelaide, South Australia.

Meg's younger brother was Columbia University history professor John Hine Mundy.

Mundy also played Mary McLeod, the lead female role, in the Broadway production of Detective Story.

[7][8] On television she played, among other roles, an antiques fancier on an episode of Alfred Hitchcock Presents, and wealthy matriarch Mona Aldrich Croft on The Doctors from 1972 to 1973 and 1975–82, leaving 3 months before the show ended.

Her film credits included roles in Eyes of Laura Mars (1978), Oliver's Story (1978), The Bell Jar (1979), and as the mother of Mary Tyler Moore's character in Ordinary People (1980), which won the Academy Award as Best Picture Of The Year.