Senior's relief work with material aid for the victims of the Franco-Prussian War of 1870 supported the National Society for Aid to Sick and Wounded in War, which was later renamed the British Red Cross. She was involved directing the practical work of handling donations.
Work with impoverished children in Surrey led to Senior's appointment in 1873, as an assistant inspector of workhouses. This post was given to her by James Stansfeld, against civil service opposition. The goal of the post was a Civil Service Report, which she framed as covering both pauper girls as school children, and their histories after school. When the Report appeared in 1875, the 1874 general election having intervened, it was the subject of heavy criticism by Carleton Tuffnell, acting in concert with The Times.
She died of 'cancer of the womb' and exhaustion on 24 March 1877, aged 48; and is buried in Brookwood Cemetery in Surrey.
G. F. Watts the artist had become a confidant of Jane Senior by the mid-1850s; they corresponded, and most of the letters have been destroyed.Octavia Hill, governess for a time to the children of Thomas Hughes, became a close friend. Senior was a friend and correspondent of the novelist George Eliot.
Jane married Nassau John Senior, son of Nassau William Senior, on 10 August 1848 at Shaw Church. Her husband was a barrister, but failed to make more than a desultory career in the law. From 1860 they lived in Clapham, taking lodgers.
The marriage was unhappy. They had a son Walter Nassau (1850-1933). He married Mabel Barbara Hammersley, daughter of Hugh Hammersley and his mother's friend Dulcibella Eden, in 1888.
Dorothea Murray Hughes (1891-1952), daughter of Senior's brother Hastings Hughes, was a nurse and aid worker. She wrote Jane Elizabeth Senior: A Memoir (1915).