You have mentioned a Thomas Keys Job who married Eliza Job, and that those families lived near Syonee. Where do the Fosters fit in?
Syonee/Syanee is in the parish of Donacavey. I checked the tithe applotment records for that parish for the surnames Job(b) and Keys. I found 5 Jobb and 3 Keys. None in Syanee but those names are found in nearby townlands. There are also some Foster farms there too.
http://cotyroneireland.com/tithe/donacavey1827.html
The folk in the tithes were farmers. Labourers, servants etc and folk without land would not be listed in the tithes, so this is not a comprehensive list of all residents. Just an indicative list.
Griffiths Valuation for 1860 lists 2 Jobb households in Syonee. One was plot 8 which was held by Andrew Jobb and was an 18 acre farm. The other was plot 11a held by John Jobb. It was 11a and was just outbuildings and 27 acres. (He had sublet the farmhouse and so didn’t live there. I’d guess he lived with his relative Andrew).
Here’s Andrew in the 1901 census:
http://www.census.nationalarchives.ie/pages/1901/Tyrone/Tattymoyle/Syonee/1744004/
The family was Church of Ireland.
You can use the Valuation Revision records to follow the 2 properties forward from Griffiths to see when they changed their hands. Those records are on the PRONI site.
I can’t say for certain who Andrew married but it may be Elizabeth Emerson, on 29.11.1850 at Tempo Church of Ireland. If so, according to rootsireland’s transcript, Andrew’s father was Thomas Jobb, farmer, of Killyberry. Bride & Groom were both 22 when they married.
There’s a will on the PRONI wills site which records that Thomas Jobb of Killyberry also owned a farm in Syanee. The will names 5 or 6 sons and daughters.
Letters of Administration (with the Will annexed) of the personal estate of Thomas Jobb late of Killyberry County Tyrone Farmer deceased who died 9 December 1875 at same place were granted at Armagh to Charles Jobb and Hugh Jobb both of Killyberry (Fintona) aforesaid Farmers the Sons and Residuary Legatees.
Donacavey/Fintona Church of Ireland records start in 1800. There’s a copy in PRONI (the public record office) in Belfast. You might want to search them to see if you can find your family there.
Syanee family in 1911:
http://www.census.nationalarchives.ie/pages/1911/Tyrone/Tattymoyle/Syonee/872652/
Andrew is dead and 2 sons have returned to live with their mother. Both were retired police officers. One with the Royal Irish Constabulary and the other with the Dublin Metropolitan Police. You should be able to get details of their careers if you are interested in that.
A couple of probate abstracts relating to the Syonee & Killyberry family:
Jobb William John of Sionee Fintona county Tyrone pensioner died 19 August 1926 Administration Londonderry 24 September to Robert Jobb pensioner. Effects £191 7s.
Jobb Alexander of Killaberry Fintona county Tyrone retired farmer died 29 December 1946 Probate Londonderry 10 March to Isabella Hamilton widow. Effects £304 5s.
I noticed this Keys family farming in Syanee in 1911:
http://www.census.nationalarchives.ie/pages/1911/Tyrone/Tattymoyle/Syonee/872647/
Those Keys & Jobb farms were very close together so you may well be on the right track for locating your ancestors. Checking Donacavey Church of Ireland baptism & marriage records would seem the next step forward.