Princess Victoria of Hesse and by Rhine
Princess Victoria of Hesse and by Rhine, later Victoria Mountbatten, Marchioness of Milford Haven
(Victoria Alberta Elisabeth Mathilde Marie; 5 April 1863 – 24 September 1950) was the eldest daughter of Louis IV, Grand Duke of Hesse and by Rhine (1837–1892), and his first wife Princess Alice of the United Kingdom (1843–1878), daughter of Queen Victoria and Prince Albert of Saxe-Coburg and Gotha.
Her mother died while her brother and sisters were still young, which placed her in an early position of responsibility over her siblings.
Over her father's disapproval, she married his first cousin Prince Louis of Battenberg, an officer in the United Kingdom's Royal Navy, and lived most of her married life in various parts of Europe at her husband's naval posts and visiting her many royal relations.
She was perceived by her family as liberal in outlook, straightforward, practical and bright.
During World War I, she and her husband abandoned their German titles and adopted the British-sounding surname of Mountbatten, which was simply a translation into English of the German "Battenberg".
Two of her sisters—Elisabeth and Alix, who had married into the Russian imperial family—were killed by communist revolutionaries.
She was the maternal grandmother of Prince Philip, Duke of Edinburgh, the consort of Queen Elizabeth II.
George Mason II
George Mason II( 1660 – 1716) was an early American planter and statesman.
Mason was the grandfather of George Mason IV, a Founding Father of the United States.
George Mountbatten, 2nd Marquess of Milford Haven
Captain George Louis Victor Henry Serge Mountbatten, 2nd Marquess of Milford Haven, (6 December 1892 – 8 April 1938), born Prince George of Battenberg, styled Earl of Medina between 1917 and 1921, was a Royal Navy officer and the elder son of Louis Mountbatten, 1st Marquess of Milford Haven
(Prince Louis of Battenberg) and Princess Victoria of Hesse and by Rhine.
His subsidiary titles included Viscount Alderney.
Lewis Gordon, 3rd Marquess of Huntly
Lewis Gordon, 3rd Marquess of Huntly( c. 1626–1653) was a Scottish nobleman.
He was the third son of George Gordon, 2nd Marquess of Huntly.
George Mountbatten, 4th Marquess of Milford Haven
George Ivar Louis Mountbatten, 4th Marquess of Milford Haven( born 6 June 1961), styled Earl of Medina before 1970, is a British peer and businessman.
Georgina Kennard
Georgina, Lady Kennard( née Wernher; 17 October 1919 – 28 April 2011) was a member of the British aristocracy who has been described as" one of the best connected women in the country" and" a distant cousin of the Queen and one of her closest friends".
Lady Kennard was the mother of Alexandra Hamilton, Duchess of Abercorn, and Natalia Grosvenor, Duchess of Westminster.
She was also an aunt of Maralyn Ramsay, Countess of Dalhousie, the sister of Myra Alice Wernher, Lady Butter, and a first cousin once removed of George Mountbatten, 4th Marquess of Milford Haven.
She was the godmother to the Queen's second son, Prince Andrew, Duke of York, who attended her funeral in person.
David Mountbatten, 3rd Marquess of Milford Haven
David Michael Mountbatten, 3rd Marquess of Milford Haven,( 12 May 1919 – 14 April 1970), styled Viscount Alderney before 1921 and Earl of Medina between 1921 and 1938, was the son of the 2nd Marquess of Milford Haven and Countess Nadejda de Torby.
William Herbert, 2nd Marquess of Powis
William Herbert, 2nd Marquess of Powis( c. 1660–1745) was a Welsh aristocrat and Jacobite supporter.
James Gordon, 2nd Viscount Aboyne
James Gordon, 2nd Viscount Aboyne( c. 1620 – February 1649) was the second son of George Gordon, 2nd Marquess of Huntly, a Scottish royalist commander in the Wars of the Three Kingdoms.
John Butler, 2nd Marquess of Ormonde
John Butler, 2nd Marquess of Ormonde, KP( 24 August 1808 – 25 September 1854) was an Irish politician and peer.

Question: Who is the maternal grandfather of George Mountbatten, 2Nd Marquess Of Milford Haven?
Answer: Louis IV, Grand Duke of Hesse