William I, Count of Burgundy
William I (1020 – 12 November 1087), called the Great ("le Grand" or "Tête Hardiethe Stubborn"), was Count of Burgundy from 1057 to 1087 and Mâcon from 1078 to 1087.
He was a son of Renaud I and Alice of Normandy, daughter of Richard II, Duke of Normandy.
William was the father of several notable children, including Pope Callixtus II.
In 1057, he succeeded his father and reigned over a territory larger than that of the Franche-Comté itself.
In 1087, he died in Besançon, Prince-Archbishopric of Besançon, Holy Roman Empire -- an independent city within the County of Burgundy.
He was buried in Besançon's Cathedral of St John.
William married a woman named (a.k.a. Etiennette).
Children of Stephanie (order uncertain):
Isabella of Bourbon
Isabella of Bourbon, Countess of Charolais( 1434 – 25 September 1465) was the second wife of Charles the Bold, Count of Charolais and future Duke of Burgundy.
She was a daughter of Charles I, Duke of Bourbon and Agnes of Burgundy, and the mother of Mary of Burgundy, heiress of Burgundy.
Reginald I, Count of Burgundy
Reginald I, Count of Burgundy( aka Renaud I, Count Palatine of Burgundy) was the second Count of the Free County of Burgundy.
Born in 986, he was the son of Otto- William, Count of Burgundy( the first Count) and Ermentrude de Roucy.
In 1016, Reginald married Alice of Normandy.
He succeeded to the County on his father's death in 1026.
Reginald was succeeded by his son, William I, on his death in 1057.
Reginald married Alice and had the following children:
Reginald II, Count of Burgundy
Reginald II, Count Palatine of Burgundy and Count of Mâcon, Vienne and Oltingen, was born in 1061; he was the eldest son of William I of Burgundy and brother to Stephen I of Burgundy, his successor, as well as to Pope Callixtus II.
He succeeded to the County, aged 25, on his father's death in 1087, also gaining the title of Count of Mâcon.
From his wife, the Countess Regina of Oltingen, he inherited—among others — the title of Count of Oltingen, they were the parents of William II of Burgundy.
The place and date of his death is uncertain, as is his potential participation in the First Crusade.
His death is dated either to 1095, prior to the First Crusade or to circa 1102 in the Holy Land along with his brothers Stephen I and Hugh, archbishop of Besançon.
Sibylla of Burgundy, Duchess of Burgundy
Sybilla of Burgundy( 1065 – 1103), was a French noble, Duchess consort of Burgundy by marriage to Eudes I, Duke of Burgundy.
She was a daughter of William I, Count of Burgundy and Stephanie.
She was married to Eudes I, Duke of Burgundy in 1080.
Children:
Alice of Normandy
Alice or Adeliza, Adelaide or Aelis
(c. 1002 – 1038) was a countess consort of Burgundy, the daughter of Richard II, Duke of Normandy (972–1026) and Judith of Brittany.
She married Reginald I, Count of Burgundy and had the following children:
Henry, son of Robert I of Burgundy
Henry of Burgundy (c. 1035 – January 27, 1070/1074), called the Gallant ("le Damoiseau"), was the eldest surviving son and heir of Robert I, Duke of Burgundy, second son of Robert II of France, and his wife, Helie of Semur, granddaughter of Henry I, Duke of Burgundy.
Little is known about his life.
He died shortly before his father and was never duke himself.
The name of Henry's wife is not known, though both Sibylla and Clémence have been suggested.
The first of these derives from an undated obituary from Besançon, Sainte-Etienne, naming "Sibilla, mater ducus Burgundie" (Sibylla, mother of the Duke of Burgundy), it being reasoned that since she is not called duchess, she must have been married to the sole father of a duke who was not a duke himself, Henry.
However, it has been argued by Jean Richard that this is a reference to Sibylla of Burgundy, Duchess of Burgundy, mother of the then-ruling duke, Hugh II.
Richard proposed based on the name's repeated use among the descendants of her son Odo I, Duke of Burgundy that she may have been named Clémence, although Odo's wife had a sister, Clementia of Burgundy, who could have been the inspiration for its use among their descendants.
Based on the use of the byname "Borel" by Odo I, genealogist Szabolcs de Vajay proposed that his mother was the daughter of Berenguer Ramon I, Count of Barcelona and his third wife, Guisle of Lluca, and hence granddaughter of Ramon Borrell, Count of Barcelona, although there is no documentary evidence that this was the case.
Henry's wife died on or after July 6, 1074.
Humbert II, Count of Savoy
Umberto II, nicknamed the Fat( 1065, Carignano, Piedmont – 19 October 1103), was Count of Savoy from 1080 until his death in 1103.
He was the son of Amadeus II of Savoy.
He was married to Gisela of Burgundy, daughter of William I, Count of Burgundy, and had 7 children:
Florine of Burgundy
Florine of Burgundy( 1083–1097) was a French crusader.
She was the daughter of Eudes I, Duke of Burgundy and Sybilla of Burgundy.
Her maternal grandfather was William I, Count of Burgundy.
Florine was married to Sweyn the Crusader, a son of Sweyn II of Denmark.
Robert, Count of Burgundy
Robert, Count of Burgundy( 1300 – 1315) was the son of Otto IV, Count of Burgundy and Mahaut, Countess of Artois.
He was count of Burgundy between 1302 and 1315.
He died in 1315, and was succeeded by his sister, Joan II, and brother- in- law, Philip II, later queen and king of France.

Question: What is the date of death of William I, Count Of Burgundy's mother?
Answer: 1038