Anne of Bohemia (1290–1313)
Anne of Bohemia( 1290 –1313) was the eldest surviving daughter of Wenceslaus II of Bohemia and Poland and his first wife Judith of Habsburg.
Her siblings included Elisabeth of Bohemia and Wenceslaus III of Bohemia.
Beatrice of Bohemia
Beatrice of Bohemia( 1225–1290) was a daughter of King Wenceslaus I of Bohemia and his wife Kunigunde of Hohenstaufen.
She married Margrave Otto III and was the mother of:
Žito
Žito( also called Ziito, fl. fourteenth century) was a court- magician of Wenceslaus IV of Bohemia.
Podevin
Podevin was a page of Duke Wenceslaus I of Bohemia in the 10th century.
He is immortalized because of his appearance in the Christmas carol" Good King Wenceslaus":
Margaret of Bohemia, Duchess of Wroclaw
Margaret of Bohemia( 21 February 1296 – 8 April 1322) was a daughter of Wenceslaus II of Bohemia and his first wife, Judith of Habsburg.
Margaret of Bohemia, Duchess of Bavaria
Margaret of Bohemia( 1313–1341) was the daughter of King John of Bohemia by his first wife Elisabeth of Bohemia( 1292–1330).
Wenceslaus I of Bohemia
Wenceslaus I (c. 1205 – 23 September 1253), called One-Eyed, was King of Bohemia from 1230 to 1253.
Wenceslaus was a son of Ottokar I of Bohemia and his second wife Constance of Hungary.
Adam Wenceslaus, Duke of Cieszyn
Adam Wenceslaus of Cieszyn( 12 December 1574 – 13 July 1617), was a Duke of Cieszyn from 1579 until his death.
He was the second but only surviving son of Wenceslaus III Adam, Duke of Cieszyn, by his second wife Sidonia Katharina, daughter of Francis I, Duke of Saxe- Lauenburg.
His older half- brother, Frederick Casimir, only son of Wenceslaus III Adam's first marriage, died a few years before he was born, in 1571.
Constance of Hungary
Constance of Hungary (c. 1180 – 6 December 1240) was the second Queen consort of Ottokar I of Bohemia.
Sophia of Bavaria
Sophia of Bavaria (1376 – 4 November 1428) was a Queen of Bohemia and the spouse of Wenceslaus, King of Bohemia and King of the Romans.
She was briefly interim regent of Bohemia after the death of Wenceslaus in 1419.

Question: What is the date of death of Wenceslaus I Of Bohemia's mother?
Answer: 6 December 1240