Isabel Howard was the wife of Paul Howard, the mother of Beverly Howard (later Crusher) and the maternal grandmother of Wesley Crusher. Isabel, having married into the family, and her daughter Beverly were the first two Howard women who did not have green eyes. (TNG: "Conundrum", "Sub Rosa")
As a child, Beverly often found herself getting in trouble with her parents because of her tendency to speak without thinking. (TNG: "Attached")
Isabel died when Beverly was very young, leaving Beverly's grandmother, Felisa Howard, to care for her. Beverly remembered her mother well, including her face, her scent, and the fact that she loved her very much. (TNG: "Sub Rosa")
In 2401, Beverly voiced anger over losing both her parents to "the stars", along with her husband Jack R. Crusher, and her son Wesley. (PIC: "Seventeen Seconds")
Isabel's name was briefly glimpsed on Beverly's personnel file in "Conundrum". The circumstances surrounding the death of Beverly's parents are vague. It is possible they died at the fabled Arvada III disaster. However, Beverly said in "Sub Rosa" that she had relatively few memories of her parents compared to her grandmother, and she seemed to remember more about Arvada III in "The Arsenal of Freedom".
An unseen invitation to Beverly and Jack R. Crusher's wedding created for the Picard family album in Star Trek Generations mistakenly shows Paul and Isabel as being alive in 2348, when Beverly was twenty-four years old.