Reps for the 'RHOBH' star tell us Maureen passed away Saturday morning at her New Jersey home while surrounded by family. We're told she succumbed to a long battle with cancer that she fought through courageously.

Both Camille and Maureen have been afflicted with genetic cancers, and each of them have been champions of the cause over the past decade. Maureen was diagnosed with several types of cancer throughout her life -- including ovarian, colon and most recently, bladder.

Maureen was incredibly important to Camille -- as the reality star would often throw up throwback photos of her mom for Mother's Day and other holidays to honor her.

Camille's mother also appeared in a handful of 'Real Housewives' episodes ... including during Camille's Hawaiian wedding to her David Meyer. The fact Maureen was able to make it at all was clearly special to her daughter ... and Mama Bear even got some camera time.

We're told funeral arrangements for Maureen are pending. She's survived by her two children, as well as her grandchildren.

Maureen was 75.