Thanks you all for the replies. It looks like there is one of the houses in Nierneys Court that may correspond with Smith's Cottages that still have a Kelly in it but it is difficult to know if it is number 13. Also, with it being what appears to be somewhat of a transitory area and Kelly being a common name it is difficult to tell.
In answer to Sinann - John's father name was also John (you see my problem!). They both have the occupation of labourer. He is listed as age 20 when he got married. That is all I have for him.
Mary's father is James (deceased) - her address is 6 Dorset Place - I already have her family.
Their marriage cert is from St Josephs in Berkeley Road.
Mary and John themselves are living at Dorset place in the 1901 census -
http://www.census.nationalarchives.ie/pages/1901/Dublin/Inns_Quay/Dorset_Place/1324043/Thank you all.
Sharon