perhaps look into the church where they married?
a lot of scottish people stuck with a particular church.
ie all family baptisms, marriages and funerals were held at the one church (often by the same minister over a period of time)
it might be easier to work backwards from the cemetery to the death certificate if your family is buried in a particular cemetery.
but i am guessing you dont know where she is buried?
not sure i can help any more...... tanya