Hildigard Took was the daughter of Gerontius, the Old Took. Hildigard was the second child and first daughter of Gerontius and Adamanta Chubb Took. Her older brother was Isengrim III. She had ten younger siblings - Isumbras IV, Hildigrim, Isembold, Hildifons, Isembard, Hildibrand, Belladonna, Donnamira, Mirabella, and Isengar. Hildigard was born sometime between 2832 and 2838 - possibly in 2835. She died young, though her date of death is not known. According to one source (HoME XII, p. 107), she died in 2855, but this may not be accurate.
Source: Appendix C of LotR: Took genealogy, p. 381 The History of Middle-earth, vol. XII, The Peoples of Middle-earth: "The Family Trees," p. 107