I have a copy of Dublin 1901 census index to the North Strand, Clonliffe Road and Summerhill District, compiled by Marie Keogh.
Murray - There are no listings for Philip or Mary Murray living at 3 Summerhill.
But there is a Mary Murray living at 8 Ballybough Road.
Philip could have been away with the army, or they could be living in army lodgings in the barracks.
Williams - There are 10 listings. If you like you could forward the first names and i can check if they are included.
Regards
Noel Gorman
Dublin, Ire