The accomplished pianist's death came just a week before her extraordinary story of surviving two years in a Nazi prison camp through devotion to music and her son is up for an Oscar.
Herz-Sommer died in a hospital after being admitted Friday with health problems, daughter-in-law Genevieve Sommer said.
"We all came to believe that she would just never die," said Frederic Bohbot, a producer of the documentary The Lady in Number 6: Music Saved My Life.
The film, directed by Oscar-winning filmmaker Malcolm Clarke, has been nominated for best short documentary at the Academy Awards next Sunday.
Herz-Sommer, her husband and her son were sent from Prague in 1943 to a concentration camp in the Czech city of Terezin – Theresienstadt in German – where inmates were allowed to stage concerts in which she frequently starred.
An estimated 140,000 Jews were sent to Terezin and 33,430 died there. About 88,000 were moved on to Auschwitz and other death camps, where most of them were killed. Herz-Sommer and her son, Stephan, were among fewer than 20,000 who were freed when the notorious camp was liberated by the Soviet army in May 1945.
She remembered that, at Terezin, it was the music that kept them going.
"These concerts, the people are sitting there, old people, desolated and ill, and they came to the concerts and this music was for them our food. Music was our food. Through making music we were kept alive," she once recalled.
"When we can play it cannot be so terrible."
Though she never learned where her mother died after being rounded up, and her husband died of typhus at Dachau, in her old age she expressed little bitterness.
"We are all the same," she said. "Good, and bad."
Anita Lasker-Wallfish, a friend and fellow concentration camp survivor, said Herz-Sommer was still lively during a visit last week.
"She was a real optimist," she said, adding that the pair used to play Scrabble together frequently until Herz-Sommer's eyes failed her. "She was feeling very unwell and she went to the hospital last Friday. I think she had enough."
She added that Herz-Sommer lived a modest life, and would probably balk at the media attention directed at her death.
"She didn't think of herself as anybody very special," she said. "She would hate any fuss to be made."