I realize this is an old post.
I see you have referenced Cattan so I am going through a lot of my findings and I am not really sure how this all fits together but....
Other records show a Thomas Faughnan was born Mar 02, 1865 to Michael Faughnan and Ellen McGarry, Rinn. There is some inconsistency with the dates below backed into from 1901 census. I realize this is not the Thomas you are referencing in the 1901 census from Annaduff but given the names of the niece and nephew (Heslin) living with this widower I thought it may be a consideration.
* Thomas Faughnan Listed on the 1901 as a 45 yr old farmer living in Cattan and as being married but does not mention his wife. That being so it backs into a date of birth of 1856. He is listed as living with his niece Ellen Heslin and nephew Michael Heslin In the 1911 census he is listed as as a widower living alone.
* Catherine Faughnan was married to John Heslin in Gortletteragh on Jan 01, 1887. John is further listed in the 1901 census as a 58 yr old widower living in Cattan which makes his year of birth 1845.
Their children were Ellen Heslin baptized Dec 12, 1877 and Michael Heslin baptized May 31, 1884