Sue,
Back Street Strabane is in the civil parish of Camus (RC parish of Clonleigh). Clonleigh's records start in 1773 (with some gaps). You can view them on the nli site (free) plus rootsireland should have them too (subscription site). There’s a gap in the births and marriages between around 1781 and 1843 which is probably the period your couple married in.
The Valuation Revision records on the PRONI website show that Hugh’s property in Back St remained in his name until 1872 when he was succeeded by William Wray. Doesn’t mean he was living there (though it might) more likely the clerks hadn’t caught up with their record keeping.
There’s a death for a Hugh McCrossan on 3rd May 1864 aged 78, registered in Strabane. However it appears he lived in Newtownstewart area so probably not your ancestor. Suspect your Hugh may have died before 1.1.1864 when death registration began, in which case it may be tricky to locate his exact death. Griffiths was compiled in 1858 which suggests he was alive then. If widow and daughter arrived in Canada in 1860, then perhaps he died around 1859?
You may struggle to find much on the Ward family. The records probably don’t exist. McCrossan is a very common name in the Strabane area and no shortage of marriages involving folk with that surname.
Possibly DNA testing may be a way of matching with others who have additional information about where the family originate. Family Tree DNA reportedly has more people with Ulster roots than any other company. That obviously increases the chances of finding a match. You might want to try them or, if you have already tested, you can transfer your results to them for no fee.
The North of Ireland Family History Society is running an Ulster DNA project in conjunction with FTDNA and can offer testing kits at a reduced price. http://www.nifhs.org (Go to DNA project on the website).
