Diana Guardato
Diana Guardato was a member of the aristocratic Patrician Guardato family, and had three children with King Ferdinand I: Diana Guardato is the 16th- Great Grandmother of His Royal Highness Albert II of Belgium, 15th- Great Grandmother of His Majesty Juan Carlos
I of Spain, 17th- Great Grandmother of Philippe of Belgium, 14th- Great Grandmother of His Majesty Manuel II of Portugal, 16th- Great Grandmother of Grand Duke Henri, as well as many others.
Beatrice of Sicily (1326–1365)
Beatrice of Sicily (5 September 1326 – 12 October 1365) was a daughter of Peter II of Sicily and his wife Elisabeth of Carinthia.
She was born into the House of Aragon.
Yevdokiya Lopukhina
Tsarina Eudoxia Feodorovna Lopukhina( in Moscow – in Moscow) was a Russian Tsaritsa as the first wife of Peter I of Russia, and the last ethnic Russian and non-foreign wife of a Russian monarch.
They married on 27 January 1689 and divorced in 1698.
She was the mother of Tsarevich Alexei Petrovich and the paternal grandmother of Peter II of Russia.
Peter II of Russia
Peter II Alexeyevich (Russian: Пётр II Алексеевич, "Pyotr II Alekseyevich")  reigned as Emperor of Russia from 1727 until his untimely death.
He was the only son of Tsarevich Alexei Petrovich (son of Peter the Great by his first wife, Eudoxia Lopukhina) and of Charlotte Christine of Brunswick-Lüneburg.
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.
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.
Charlotte Christine of Brunswick-Wolfenbüttel
Charlotte Christine Sophie also known as Sophie Charlotte or simply Charlotte (28 August 1694, Wolfenbüttel – 2 November 1715, Saint Petersburg), was the wife of Tsarevich Alexei Petrovich of Russia.
She was the daughter of Louis Rudolph, Duke of Brunswick-Wolfenbüttel and Princess Christine Louise of Oettingen-Oettingen.
She was also the great aunt of Queen Marie Antoinette of France.
Abdul-Vahed Niyazov
' of Russia.
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.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.

Question: Who is the maternal grandmother of Peter Ii Of Russia?
Answer: Princess Christine Louise of Oettingen-Oettingen