Grand Duchess Elena Pavlovna of Russia
Grand Duchess Elena Pavlovna of Russia, Hereditary Grand Duchess of Mecklenburg( 24 December 1784[ OS 13 December] – 24 September 1803) was a daughter of Grand Duke, later Tsar Paul I of Russia and his second wife Sophie Dorothea of Württemberg.
After marrying the son and heir of the Grand Duke of Mecklenburg- Schwerin she ceased to use her Russian title.
Princess Charlotte of Württemberg
Princess Charlotte of Württemberg (9 January 1807 – 2 February 1873) was later known as Grand Duchess Elena Pavlovna, the wife of Grand Duke Michael Pavlovich of Russia.
He was the youngest son of Emperor Paul I of Russia and Duchess Sophie Dorothea of Württemberg.
Prince Dmitri Alexandrovich of Russia
Prince Dmitri Alexandrovich of Russia( 15 August 1901 – 7 July 1980) was the fourth son and fifth child of Grand Duke Alexander Mikhailovich of Russia and Grand Duchess Xenia Alexandrovna of Russia.
He was a nephew of Tsar Nicholas II of Russia.
Princess Elizabeth of Greece and Denmark
Princess Elisabeth of Greece and Denmark( 24 May 1904 – 11 January 1955) was the middle daughter of Prince Nicholas of Greece and Grand Duchess Elena Vladimirovna of Russia.
Anatoly Ionov (Romanov claimant)
Anatoly Ionov( born 1936) is a Russian man who claims to be the son of Grand Duchess Anastasia Nikolaevna of Russia.
Duchess Marie of Mecklenburg-Schwerin
Duchess Marie of Mecklenburg-Schwerin (later Grand Duchess Maria Pavlovna of Russia, known as "Miechen" or "Maria Pavlovna the Elder"; 14 May 1854 – 6 September 1920) was born Marie Alexandrine Elisabeth Eleonore of Mecklenburg-Schwerin, daughter of Grand Duke Frederick Francis II of Mecklenburg-Schwerin and Princess Augusta Reuss of Köstritz.
A prominent hostess in St Petersburg following her marriage to the Grand Duke Vladimir Alexandrovich of Russia
, she was known as the "grandest of the grand duchesses" and had an open rivalry with her sister-in-law the Empress Maria Feodorovna.
Grand Duchess Elena Vladimirovna of Russia
Grand Duchess Elena Vladimirovna of Russia (17 January 1882 – 13 March 1957), sometimes known as Helen, Helena, Helene, Ellen, Yelena, Hélène, or Eleni, was a Russian grand duchess as the only daughter and youngest child of Grand Duke Vladimir Alexandrovich of Russia and Duchess Marie of Mecklenburg-Schwerin.
Her husband was Prince Nicholas of Greece and Denmark
and they were both first cousins of Emperor Nicholas II of Russia.
Abdul-Vahed Niyazov
' of Russia.
Grand Duchess Olga Pavlovna of Russia
Grand Duchess Olga Pavlovna of Russia  was a "Grand Duchess of Russia" as the second youngest daughter and seventh child of Emperor Paul I of Russia and his empress consort, Sophie Dorothea of Württemberg.
Grand Duchess Maria Vladimirovna of Russia
Grand Duchess Maria Vladimirovna of Russia (born 23 December 1953 in Madrid) has been a claimant to the headship of the Imperial Family of Russia (who reigned as Emperors and Autocrats of All the Russias from 1613 to 1917) since 1992.
Although she has used Grand Duchess of Russia as her title of pretence with the style Imperial Highness throughout her life, her right to do so is disputed.
She is a great-great-granddaughter in the male line of Emperor Alexander II of Russia.

Question: When did Grand Duchess Elena Vladimirovna Of Russia's mother die?
Answer: 6 September 1920