I would argue that there are a number of ways in which Alexander Graham Bell assisted the Keller family. He made a huge difference in the life of Helen Keller, who was blind and deaf as the result of an illness she suffered as an infant.
Having been advised by another doctor to see Dr. Bell, the family travelled to Washington, and Helen recalls in her autobiography feeling at once "the tenderness which endeared Dr. Bell to so many hearts." Helen had no idea that this meeting would be the start of a changed life for her. On Dr. Bell's advice, Helen's father made contact with the Perkins Institution in Boston, and they found her a teacher, Anne Mansfield Sullivan. It was Anne who opened up the world of communication to Helen, and she recalls the day of Miss Sullivan's arrival as the most important day of her life.
Later, when Helen was accused of plagiarism, Dr. Alexander Graham Bell assisted Miss Sullivan in figuring out how Helen had come to subconsciously know the story of "The Frost Fairies."
Dr. Bell became a hugely influential character in Helen's life. She recalls visiting the World's Fair with him and having a splendid time. She spent lots of time with him at his home, being told about the experiments he was working on and "helping him fly kites." He helped the Keller family by bringing moments of joy into Helen's life.
In her autobiography, Helen's affection for Dr. Bell is abundantly evident. She had immense respect for his work with deaf children and for his influence over the way that deaf children were taught.