According to Civil War records at Fold3.com, John was captured at the Battle of Spotsylvania Courthouse on 12 May 1864, and transported to Elmira Prison in New York. He died there on 13 Feb 1865 of chronic diarrhea, and was bured in Woodlawn National Cemetery along with all his effects. (See http://www.blueandgraymarching.com/articles/prisoners-of-grant-the-punc.html and http://en.wikipedia.org/wiki/Elmira_Prison)

1850 census of Pulaski Co., Virginia, district 48, enumerated 4 Aug, lists on p. 36 as family #266/254:
John Quesenberry, 24, laborer; Nancy, 25; Leander, 4; Montgomery, 3; Mary E., 1. All born in Virginia.

John’s brother William is recorded three households below.

1860 census of Pulaski Co., Virginia, Western district, enumerated 11 July, lists on p. 58 as family #394/395:
John Quesenberry, 34, farmer; Nancy, 36; Leander, 14; James M., 13; Mary E., 11; John R., 7; Sarah, 5; Wm, 3; Stephen, 7/12. All born in Virginia.

After John’s death in the Civl War, the family was broken up. In the 1870 census, the two older boys, Leander and James Montgomery, were married and heads of household - Leander in Raleigh Co., WV, and James in Pulaski Co., VA with his first wife Rhoda Nunn. Sarah, Joseph, and Lucinda are recorded with Nancy's parents, Peter and Rebecca (Breeding) Moore. William is recorded with Wiley Ashworth. Stephen Jasper is living as a farm hand with James B. Owens. Elizabeth (Betty) is living with her brother James Montgomery and his wife. (Nearly all the Quesenberry’s in Pulaski Co in 1870 were recorded as Crusenberry, presumably due to the census taker’s preferred spelling.) I cannot find Nancy, John Jr or Mary Ellen in 1870. They may have been in the process of moving between households that summer and missed the census taker, perhaps on their way to Raleigh Co., West Virginia, where Mary was married in 1873.

In 1880 Nancy is recorded in Raleigh Co., West Virginia with her daughter Mary and Mary’s husband William A. Gray as Nancy Quesenberry, mother-in-law, age 53, widowed, b. Va Va Va.