I am most grateful to Alan, who has sent me lots of information about the Dearls and Mulroys in Clontarf and in particular has sent me several maps shown below.  These maps help to explain where the DEARLs and MULROYs were living in Clontarf in the period covered by the 1901 and 1911 census.

The large Map A above is based on Griffiths map of the area, and shows the position of streets and buildings in 1850.  Alan has marked up the map to show where later streets are located.

Map B shows the situation sometime before the 1901 census was taken and after the development of the Tramway Depot which was built in around 1880, along with 15 houses located in Tramway Terrace – later known as Tram Terrace, and now called Conquer Hill Avenue. The 1901 census records show that all the houses in Tram Terrace were occupied by households headed by a man employed in the Tramway Depot – with the two end cottages (which were considerably larger) seemingly run as boarding houses for single employees at the Depot.  

Mooneys Cottages can be seen in the upper right of Map B. In the 1901 census, Thomas and Annie Dearl and their family were living at 4 Mooney's Cottages (shown in green on the above map).  The enumerator’s notes record that Mooney's cottages comprised 17 cottages, each with 2-4 rooms. The 10 members of Annie's uncle James Mulroy's family lived at number 13 and the four members of her uncle Christopher Mulroy's family lived at number 14.

Map C shows the situation after the 1901 census.  By this time, Mooney’s Cottages had been demolished, and replaced with a row of more modern houses in the new Conquer Hill Road.  This map also shows the newly built Brian Boru Street (where the Dearls lived at no 4) and Brian Boru Avenue (where three of the Mulroy families lived in nos 24, 42 and 48).  

Alan has suggested that  the MULROYs in particular (who had arrived Clontarf in the early 1860s), would have seen a dramatic development in the area from the initial isolation of Mooneys cottages evident in the Griffiths map of 1850: first with the arrival of the horse-drawn trams  in around  1890 and later the electrified tram service  which first ran on 19th Mar 1899. The old Tram sheds are now the site of the Dublin Bus Company depot.

Sources:

Griffiths Valuation  

Transport in 19thC Clontarf