1901 Irish census is not yet indexed or online (1901 and 1911 will eventually be on National Archives (Dublin) site). However, I did find a few bits on the McCreadys for you.
The two Scottish births I found earlier (Thomas and Isabella) are the correct family- 1861 Scottish Census confirms this.
1861 Census- 47 WEest Abbey St., Arbroath, Forfarshire
Thomas McCready 47 Ireland pawnbroker
wife Margaret McCready 36 Lanarkshire
dau. Catherine McCready 18 Ireland
dau. Margaret McCready 7 Arbroath scholar
son Thomas McCready 4 Arbroath
dau. Isabella McCready 2 Arbroath
servant Jessie Harney 15 Arbroath domestic servant
servant Margaret Baxter 60 Arbroath domestic servant
Wondering if Margaret was Thomas' 2nd wife as he and daughter Catherine both born in Ireland but Margaret in Scotland and also there's a big gap in ages between Catherine and other 3 children.
Will of Thomas McCready (father) - more on PRONI site:
The Will of Thomas M'Cready late of Princes-street Londonderry Pawnbroker who died 21 April 1895 at same place was proved at Londonderry by Thomas Roulston Vaughan M'Cready of William-street Londonderry Pawnbroker the sole Executor.
Census information Crown Copyright, from www.nationalarchives.gov.uk