I have done a considerable amount of research on the Kentucky Younts and note that there have been several marriages between members of the Yount and Hulett families over the years.
The earliest were in Franklin Co., KY where Catherine Yount m. Thomas Hulett on 29 March 1830 and Sarah Yount m. George Hulett on 12 March 1841. Catherine Yount b. 1818 KY and Sarah Yount b. 1820 KY were both daughters of John Yount b. 1756 VA and Nancy. Thomas Hulett b. 1815 KY and George Hulett b. 1814 KY were sons of William Hulett b. 1782 VA and Rachel Page b. 1784 SC. John Yount b. 1756 VA was the son of Hans Adam Junt b. 1729 in Basel Switzerland.
The next marriages between Younts and Huletts were in Hendricks Co., IN where Martha A. Yount m. William H. Hulett on 24 April 1860 and Lucinda Yount m. the same William H. Hulett on 14 September 1865. Martha A. Yount b. 1835 KY was the daughter of Mathias Yount b. 1805 KY and Catherine Meadows b. 1809 VA. Lucinda Yount b. 1833 KY was the daughter of Enos Yount b. 1813 KY and Elizabeth Morris b. 1806 KY. Enos Yount and Mathias Yount were brothers and sons of John Yount b. 1781 KY and Catherine b. 1796 PA. John Yount b. 1781 was the son of George "Old Soldier" Yount b. 1757 VA who was a brother of the John Yount b. 1756 VA mentioned above.
Your posting indicates that a Thomas Hulett b. 1841 KY married Lucy M. Yount b. 1843 as listed in the 1870 Census for Hendricks Co., IN and the 1880 Census for Coles Co., IL. I have not found a record of the date of this marriage so would be pleased to get that from you. Louisa(Lucy) M. Yount is the daughter of Mathias Yount b. 1805 KY and Catherine Meadows b. 1809 VA.
Your posting indicates that Catherine Yunt age 69 is listed in the household of Thomas Hulett age 39 in the 1880 Census for Coles Co., IL. It appears to me that Catherine Yunt is listed above Thomas Hulett 39 and actually belongs to the household of John S. Yunt listed on the previous page. The 1880 Census listing for Ashmore, Cole Co., IL is presented below.
Page 17 159/164 Yunt, John S. head age 34 b. 1846 KY Yunt, Judawife age 43 b. 1837 KY Yunt, Joseph V. son age 10 b. 1870 IL Yunt, Eugeneson age 6 b. 1874 IL Yunt, Coradau age 1 b. 1879 IL Hedges, Annieniece age 17 b. 1863 IL Page 18 Yunt, Catherine, mother age 69 b. 1811 VA 160/165 Hulett, Thomas head age 39 b. 1841 KY Hulett, Lucy M. wife age 36 b. 1844 KY Hulett, Ellen C. dau. age 12 b. 1868 MO Hulett, Sarah E. dau. age 8 b. 1872 IN Hulett, Hettie J. dau. age 5 b. 1875 IN
John S. Yunt b. 1846 listed as the head of household 159/164 is John S. Yount b. 1845 KY the son of Mathias Yount b. 1805 KY and Catherine Meadows b. 1809 VA discussed earlier. The Catherine Yunt mother age 69 b. 1811 VA in this listing is John S. Yount's mother Catherine Meadows b. 1809 VA who is now widowed. The Annie Hedges niece age 17 b. 1863 IL is the daughter of John S. Yount's sister Susannah b. 1833 KY who married Martin Hedges b. 1833 KY.
The Lucy M. Hulett age 36 b. 1844 KY listed as the wife of Thomas Hulett age 39 b. 1841 KY in the 160/165 household is the sister of John S. Yount b. 1846 and the daughter of Mathias and Catherine Yount.
I have reviewed the 1870 Census listings of Thomas and William Hulet in Center, Hendricks Co., IN and it appears that they may be brothers but I don't know who their parents were. The Nathaniel Hulet age 75 b. 1795 VA and the Mary Hulet age 70 b. 1800 KY in the Thomas Hulet household in 1870 is a mystery. They could be his parents or grandparents but I cannot find them listed in any earlier Censuses. Any ideas?