Since they married in Wooler, and 1841 census states bc.1785, I would suggest she was the Margaret Riddle bp.11/4/1784 Wooler, dau. of William (no mothers name shown). However, the only Riddell/Riddle couple baptising children in Wooler at this time are a William and Ann so I would say these are her parents - siblings Jane 25/2/1776, James 30/9/1787, George 17/6/1790, Robert 29/7/1793, William 24/12/1795.
Can't find a likely marriage for William and Ann though.
Annette