Not much there to base a search on – did she marry in the Kilkenny area? Is this her?
(https://familysearch.org/ark:/61903/1:1:FGXY-8XD ), Thomas Redding and Ellen Hennessy, 17 Nov 1851; citing St John, Kilk, Ire, reference 2:3LQ67CW, index based upon data collected by the Genealogical Society of Utah, Salt Lake City; FHL microfilm 101,327.
J Grenham’s link for Kilderry is https://www.johngrenham.com/records/church.php?civilparishid=1365&civilparish=Kilderry&search_type=full
Also, don’t forget that Hennessy was sometimes transcribed/written as Fennessy – one of my paternal great grandmothers in Tipperary was married as a Fennessey but baptised as Henesy.