What was the maiden name of Newton's mother?

Newton’s mother’s maiden name was Ayscough.

Hannah Ayscough came from a Lincolnshire family of prosperous yeomen. Her father was James Ayscough, and her family’s social position was somewhat above that of ordinary farmers. She married Isaac Newton Sr. in 1642, but he died only a few months before their son Isaac was born.

Newton was born prematurely at Woolsthorpe Manor and was so small that his mother reportedly said he could have fitted inside a quart mug. When Newton was about three, Hannah remarried the clergyman Barnabas Smith. She moved to live with Smith, leaving young Isaac in the care of his maternal grandmother, Margery Ayscough.

Historical spelling was not fixed in this period, so the family name can also appear as Askew or Askeu in documents. Ayscough is the conventional form used in biographies of Isaac Newton and the answer expected by a quizmaster. Newton later inherited his mother’s property and wealth, which helped support him during his early life and education.