Hi Audrey
I've found a reference to a Donald McKillop living on his own at Croft Cottage, Laggan in the 1901 census. He was aged about 91 at that time - less than you give for death age a year later but still possible? Catlodge looks pretty bleak, looking on googlemaps and the streetview, it is to the North of General Wade's military road, it looks as though there might be the foundations of a house but the resolution isn't good enough to tell. Croft cottage is listed as a historical monument - a 19th century croft - on the Canmore website. Croft cottage is west of Laggan, there's a white house beside the main road with the older croft building slightly further on.
There are two McKillops buried in Banchor Cemetery, according to
www.deceasedonline.com, its free to search but then £1.50 (ish) per stone that you want to look at.
My uncle married a McKillop from the Western Isles, that seems to be the original stronghold of the name so I'll keep digging, my brick walls just keep getting thicker, its nice to have something to do!!
All the best for the New Year
Gordon