Thyra von Westernhagen
Thyra, Princess Heinrich of Hanover( née Thyra von Westernhagen; born 14 August 1973) is a German forester and landowner.
As the wife of Prince Heinrich of Hanover, she is a princess of the House of Hanover.
Princess Caroline Wilhelmina Sophia of Hesse-Kassel
Caroline, Princess of Anhalt- Zerbst( née Princess Caroline Wilhelmina Sophia of Hesse- Kassel; 10 May 1732 – 22 May 1759) was the first wife and consort of Frederick Augustus, Prince of Anhalt- Zerbst.
Ekaterina Malysheva
Ekaterina, Hereditary Princess of Hanover( née Malysheva; born 30 July 1986) is a Russian fashion designer and filmmaker.
She is the hereditary princess of the House of Hanover through her marriage to Ernst August, Hereditary Prince of Hanover.
Prince Ernst August of Hanover (born 1954)
Ernst August, Prince of Hanover( born 26 February 1954), is head of the royal House of Hanover which held the thrones of the United Kingdom until 1901, of the former Kingdom of Hanover until 1866, and of the sovereign Duchy of Brunswick from 1913 to 1918.
As the husband of Princess Caroline of Monaco, he is the brother- in- law of Albert II, Prince of Monaco.
Grace Kelly
Grace Patricia Kelly (November 12, 1929September 14, 1982) was an American film actress who, after starring in several significant films in the early- to mid-1950s, became Princess of Monaco by marrying Prince Rainier III in April 1956.
After embarking on an acting career in 1950 when she was 20, Kelly appeared in New York City theatrical productions and more than 40 episodes of live drama productions broadcast during the early 1950s Golden Age of Television.
From 1952 to 1956 she starred in several critically and commercially successful films, usually opposite male romantic leads 25 to 30 years older than her.
In October 1953, she gained stardom from her performance in director John Ford's African-filmed adventure-romance "Mogambo", starring Clark Gable and Ava Gardner, which won her a Golden Globe Award and an Academy Award nomination for Best Supporting Actress.
In 1954 she won the Academy Award for Best Actress for her deglamorized performance in the drama "The Country Girl" with Bing Crosby.
Other noteworthy films in which she starred include the western "High Noon" (1952), with Gary Cooper; the romance-comedy musical "High Society" (1956), with Bing Crosby and Frank Sinatra; and three Alfred Hitchcock suspense thrillers in rapid succession: "Dial M for Murder" (1954), with Ray Milland; "Rear Window" (1954), with James Stewart; and "To Catch a Thief" (1955), with Cary Grant.
Kelly retired from acting at the age of 26 to marry Rainier, and began her duties as Princess of Monaco.
It is well known that Hitchcock was hoping she would appear in more of his films which required an "icy blonde" lead actress, but he was unable to coax her out of retirement.
Kelly and Rainier had three children:
Princess Caroline, Prince Albert, and Princess Stéphanie.
Kelly retained her link to America by her dual U.S. and Monégasque citizenship.
Princess Grace died at Monaco Hospital on September 14, 1982, succumbing to injuries sustained in a traffic collision the previous day.
At the time of her death she was 52 years old.
She is listed 13th among the American Film Institute's 25 Greatest Female Stars of Classical Hollywood Cinema.
Caroline, Princess of Hanover
Caroline, Princess of Hanover (Caroline Louise Marguerite Grimaldi; born 23 January 1957), is the eldest child of Rainier III, Prince of Monaco, and the American actress Grace Kelly.
She is the elder sister of Prince Albert II and Princess Stéphanie.
Until the births of her niece and nephew, Princess Gabriella and Prince Jacques, in December 2014, she had been heiress presumptive to the throne of Monaco since 2005, a position which she previously held from 1957 to 1958.
Caroline is married to Ernst August, Prince of Hanover (born 1954), the heir
to the defunct throne of the former Kingdom of Hanover, as well as the heir male of George III of the United Kingdom.
Alexandra, Princess of Leiningen
Princess Alexandra of Hanover, Duchess of Brunswick- Lüneburg, Princess of Leiningen( born 18 February 1959), is the wife of Andreas, 8th Prince of Leiningen.
Born in Hanover, Lower Saxony, Germany, Alexandra is the youngest daughter of Ernest Augustus, Prince of Hanover( 1914 – 1987), and his wife, Princess Ortrud of Schleswig- Holstein- Sonderburg- Glücksburg( 1925–1980).
Her eldest brother is Ernst August, Prince of Hanover, current head of the House of Hanover and her sister- in- law is Princess Caroline of Monaco.
Princess Alexandra of Hanover (born 1999)
Princess Alexandra of Hanover( Alexandra Charlotte Ulrike Maryam Virginia; born 20 July 1999) is the only child of Princess Caroline of Monaco and Prince Ernst August of the defunct Kingdom of Hanover.
Beatrice Borromeo
Beatrice dei Principi Borromeo Arese Taverna( born 18 August 1985 in San Candido) is a member of the ancient aristocratic House of Borromeo.
She is the wife of Pierre Casiraghi, younger son of Caroline, Princess of Hanover.
Chantal Hochuli
Chantal Hochuli, formerly Chantal, Princess of Hanover, Duchess of Brunswick and Lüneburg( born 2 June 1955) is a Swiss socialite and heiress.
She is the ex-wife of Ernst August, Prince of Hanover, the head of the German House of Hanover.

Question: Why did Caroline, Princess Of Hanover's mother die?
Answer: traffic collision