, there is a baptism record for Kate Langley born 1887, parents Samuel Langley and Mary Fitzpatrick. She was baptised at St. Andrews RC Church, Westland Row, and address given is 33 Glocester Street (correct spelling is Gloucester Street), which is on the north side of the River Liffey, across the bridge from St. Andrews (which is on the south side). Gloucester Street was/is? in the area of Dublin Docks.
Also, there is a John Langley in the Dublin Griffiths Valuation, 1854, living at Seville Place, which is also near Gloucester Street (see www.askaboutireland.ie/griffith-valuation
). The local RC church for that area is St. Laurence O'Toole, where your Samuel (father) and Anne/Mary? were married. Looks as if this John Langley might be Samuel's father, and the grandfather of Robert, Samuel jnr and Kate.
Hope the above is of interest.