His father, Gil Robbins, died earlier in April.
Robbins says his mother died on Sunday at her home in Esteban Cantu, Mexico, 12 days after her husband of almost 59 years passed away.
Mary Robbins studied music at the University of California, Los Angeles, and performed on a professional level in the 1950s.
She also earned a bachelor's degree in holistic medicine after successfully beating colon cancer through nutrition and alternative medicine. She volunteered her services at a clinic near the couple's Mexico home.
Robbins says his mother "had a calm and cheerful demeanor, a sharp wit, a gentle spirit and a generous and loving heart."
She is survived by four children and four grandchildren.
The Associated Press contributed to this report.