Who is XXX's mother?
Prince George William of Hanover
Prince George William of Hanover (Georg Wilhelm Christian Albert Edward Alexander Friedrich Waldemar Ernst Adolf Prinz von Hannover), Prince of Great Britain and Ireland, Duke of Brunswick-Lüneburg (born 28 October 1880 in Gmunden, Upper Austria, Austria-Hungary; died 20 May 1912 in Nackel, Brandenburg, Germany) was the eldest son of Ernest Augustus, Crown Prince of Hanover (1845--1923) and Princess Thyra of Denmark (1853--1933), the youngest daughter of Christian IX of Denmark (1818--1906) and Louise of Hesse-Kassel (or Hesse-Cassel) (1817--1898).
Princess Thyra of Denmark