There is an older Francis Snaith (b abt 1792) living in Escomb in 1841 and 1851. On 1851 census his birth town is Etherley. It could be him who died in 1863.
According to 1851 census Elizabeth was born in Elwick, Durham in about 1799, Sarah was born in Hamsterley in abt April / May 1841 (age 1 month on 1841 census, taken in June 1841). There is a Sarah Snaith birth reg Q2 1841 Auckland district (right district for Hamsterley).
Freereg has Sarah's baptism as Sarah with no Jane added in Hamsterley on 15 may 1841, d/o Francis (occ farmer) and Elizabeth. There is a baptism for an Elizabeth Dryden at Elwick hall on 8 May 1797 parents Simon and Ann. Francis and Elizabeth named a son Simon, so it is possible it could be the baptism.
Could this be Elizabeth listed as a widow in 1861 living at 61, West Holborn, Shields, South Shields?? I think the Coroner's death you refer to in 1856 was in South Shields from a newspaper report?? The image looks like Snaith
Elizabeth Sneath Widow 67 Grocer Haltwhistle, Northumberland
Sarah Jane Sneath 21 Hexham, Northumberland
RG09 Piece 3794 Folio 64 Page 22
There seem to be several points where this doesn't match, but I can't find this Elizabeth and Sarah before 1861 to eliminate them.
Elizabeth's changing place of birth is a bit of a mystery, Elwick is 9 miles or so from Easington (pob in 1881) and Haltwistle is some way west of Hexham.
Easington and Elwick aren't too far from Escomb and Auckland (marriage place) so I think Haltwistle is just an error. I doubt Elizabeth would have made such a major mistake in her POB, maybe the enumerator was in a hurry and copied it onto the wrong line and it was actually a neighbour's POB.
It is looking as if Francis died before census day 1861