There are a few more details on the actual image of the death registration such as he was a plasterer and the informant was his daughter, Mrs. Thos Hume. If you would like a copy of it, I can email it to you if you PM me your email address.
I found John and family on the 1901 census in Toronto.
John Cardwell, head, 24 Jul 1847, 53, born England, immigrated 1868, plasterer
Jane M Cardwell, wife, 15 Nov 1848, 52, born England
Wm Cardwell, son, 7 Aug 1874, 27, born Ontario, factory hand
John Cardwell, son, 22 May 1876, 24, born in Ontario, conductor
Henry Cardwell, son, 16 Oct 1878, 22, born in Ontario, piano mover (hard to read)
George Cardwell, son, 9 Apr 1881, 19, born in Ontario, conductor
Mary E Cardwell, daughter, 16 Jul 1888, 12, born in Ontario
Here's a link to the census entry at the free index:
http://www.rootschat.com/links/059c/ You can view the image at that site or directly at Library and Archives Canada but they have a lousy viewer (in my opinion) so it may be difficult to read.
From the 1891 census in Toronto:
John Cardwell, 43, born in England, parents born in England, plasterer
Maria J Cardwell, 42, born in England, parents born in England
William Cardwell, 16, born in Ontario, parents born in England
John Cardwell, 14, born in Ontario, parents born in England
Henry Cardwell, 12, born in Ontario, parents born in England
George Cardwell, 10, born in Ontario, parents born in England
Emma Cradwell, 7, born in Ontario, parents born in England
Mary E Cradwell 3, born in Ontario, parents born in England
I couldn't find them on the 1881 census but they should be in Guelph as George was born there just days after the census was to have been taken.
From the children's birth registrations that I found at Ancestry, their mother's name appears to have been Maria Jane Atkinson. William and Mary were born in Toronto but the others were born in Guelph.
Maria Jane Atkinson Cardwell died 18 Mar 1919 in Toronto. No parents are listed on her registration.
There is a family tree posted at Ancestry in the Public Member Trees section regarding John Cardwell and Maria Jane Atkinson. If you can't access that section of Ancestry then I would be happy to send a message to the tree owner on your behalf. If you would like me to make contact with the person, please send me your email address by PM.
Also if you would like a copy of the 1891 census image and/or the birth registrations of the children, please PM me your email address and I'll send them to you.
Jacquie