Who is Esther, Brianna Ghey's mother, and why did Rishi Sunak say she represented "the very best of humanity"?

It seems there might be some confusion in your question. Esther is not Brianna Ghey's mother, and there's no known connection between Esther and Brianna Ghey. Esther is the wife of Rishi Sunak, a British politician who has served as Chancellor of the Exchequer since February 2020. Rishi Sunak made the statement about his wife Esther during a speech in the UK Parliament, not about Brianna Ghey. As for why Rishi Sunak said Esther represented "the very best of humanity," it was likely a personal statement reflecting his admiration and respect for his wife's character and actions. Esther Sunak has been involved in various charitable endeavors, and politicians often speak highly of their spouses or family members during public appearances.