Hubba bint Hulail
Hubba bint Hulail was the grandmother of Hashim ibn' Abd Manaf, thus the great- great- great- grandmother of the Islamic" Nabī"( Prophet) Muhammad ibn Abdullah.
Tjuyu
Tjuyu( sometimes transliterated as Thuya or Thuyu) was an Egyptian noblewoman and the mother of queen Tiye, and the wife of Yuya.
She is the grandmother of Akhenaten, and great grandmother of Tutankhamun.
Petronilla of Lorraine
Petronilla of Lorraine (1082 – 23 May 1144) was Countess of Holland by marriage to Floris II, Count of Holland, and regent of the County of Holland during the minority of her son Dirk VI in 1121-1129.
She was a daughter of Theodoric II, Duke of Lorraine and Hedwig of Formbach.
Anne Denman
Anne Denman( 1587–1661) was born in Olde Hall, Retford, Nottinghamshire.
Through a fortunate second marriage with Thomas Aylesbury, she became the grandmother of Lady Anne Hyde, Duchess of York and great- grandmother of Queen Mary II and Queen Anne.
Hedwig of Formbach
Hedwig of Formbach (c.1058 – c.1090), was the daughter of Frederick, count of Formbach and of Gertrude of Haldensleben, and heiress to Süpplingenburg Castle.
She was the mother of Emperor Lothair II.
Kaoru Hatoyama
After the elections of 2009, she became more widely known as the grandmother of Prime Minister Yukio Hatoyama and his politician brother Kunio Hatoyama.
Claude Françoise de Lorraine
Claude of Lorraine (6 October 1612 – 2 August 1648) was a daughter of Henry II, Duke of Lorraine, and Margerita Gonzaga, her sister was Nicole, Duchess of Lorraine.
She married her first cousin and was the Duchess of Lorraine by marriage.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.
Gülbahar Hatun (wife of Mehmed II)
Gülbahar Hatun( 1432 – 1492) was the consort of Sultan Mehmed II, and mother of Sultan Bayezid II of the Ottoman Empire and the grandmother of Selim I.
Mona Hopton Bell
Mona Hopton Bell( 1867- 1940) was a British artist, best known for her portraits of civic figures.
She was the grandmother of the painter Jean H. Bell.

Question: Who is Petronilla Of Lorraine's maternal grandmother?
Answer: Gertrude of Haldensleben