Hi,
thomo7, welcome to RootsChat!
According to the International Genealogical Index
https://familysearch.org/search/collection/igi William Ralston and Marion Perrie were married on 30 December 1864 and had three sons, James, born 4 June 1865, William, born 1 March 1872, and Daniel, born 2 January 1874, all in Kilsyth.
Their marriage certificate will tell you the full names of both sets of parents, including their mothers' maiden names. You can view and download a digital image of the certificate at
www.scotlandspeople.gov.uk - it is pay-per-view, but reasonably priced. No need to speculate about Marion's parentage when there is an easily accessible original document that should give you the correct information.
In the 1881 census (I have a transcription of this on CD-ROM) William Ralston, 47, blacksmith, was living at 18 Brick Row, Kilsyth, with wife Marion, 45 and sons James, 15, Thomas, 12, William, 9 and Daniel, 7, all born in Kilsyth. You can view the original of this census at Scotland's People as above. (I have not yet found an index listing of Thomas' birth.)
The IGI also says that Marion, daughter of Robert Perrie and Ann Robertson, was baptised in Rutherglen on 11 February 1838. Therefore she would have been 43 on the date of the 1881 census. So unless both her age and her birthplace are wrong in the 1881 census, it seems unlikely that she is tthe wife of William Ralston.
See how you get on with that marriage certificate, and come back to us with any more questions.