The documentary was written and directed by Ephron's son Jacob Bernstein, who explained to ABC News' Chris Connelly the familial meaning behind the documentary's title.
"Well my grandmother was a writer and she would say, 'Everything is copy,'" Bernstein said. "And the meaning of the phrase was this aggravating, sad thing that happened to you today is gonna be a funny story later on."
"So that became sort of my mother's mantra," he said.
As a screenwriter, Ephron was beloved by generations of movie fans for "When Harry Met Sally." As a director of films such as "Sleepless in Seattle," Ephron smashed Hollywood's glass ceiling.
Ephron even turned the 1979 demise of her marriage to Watergate journalist Carl Bernstein -- Jacob's father -- into the hit movie "Heartburn," starring Meryl Streep.
Bernstein -- who spoke with Connelly at Los Angeles deli Langer's, which Ephron believed made the greatest pastrami sandwich in the world -- lost his mom to leukemia four years ago. The documentary explores why she chose not to disclose her illness publicly, telling only a very small circle of family and friends.
"I think she just had no interest in being a victim," Bernstein said. "It was unthinkable to her."
Today, Bernstein says he most misses his mom's "trenchant observations about the world."
"I'm sad that she wasn't here for the #OscarsSoWhite controversy," Bernstein said, referring to the protests that erupted after an all-white slate of Oscar acting nominees for this year's awards.
"I think she probably would have been boycotting the Oscars because 'Inside Out' wasn't nominated for Best Picture, and I think she would have found that sexist since 'Up' was," Bernstein said. "That's my guess.”
"Everything is Copy" airs Monday, March 21, at 9 p.m., EST, on HBO.