Bolesław Januszowic
Bolesław Januszowic (1385/86 – ca. 4 May 1424), was a Polish prince member of the House of Piast.
He was the second son of Duke Janusz I of Warsaw and Danutė of Lithuania, a daughter of Kęstutis.
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.
Hüma Hatun
Hüma Hatun (1410 ‒ September 1449) was the fourth wife of Ottoman Sultan Murad II and mother of Mehmed II and the grandmother of Bayezid II.
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.
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.
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.
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.
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.
Danutė of Lithuania
Danutė of Lithuania (baptized "Anna"; ca.
1358 –
26 November 1424), was a Lithuanian princess of the Gediminid dynasty and by marriage Duchess of Warsaw.
She was a daughter of Kęstutis, Grand Duke of Lithuania, and his second wife Birutė.

Question: Who is the maternal grandmother of Bolesław Januszowic?
Answer: Birutė