If there was indeed a will, it will be listed in the annual calendars of confirmations. These are large printed book, and there are copies in various libraries including the National Archives of Scotland in Edinburgh, the Mitchell Library in Glasgow, and West Lothian Archives. There is an online index to Scottish wills 1530-1901, but it does not list your Ann Clayton.
If her mother was the proprietor, there would be a record of the change of ownership in the Registers of Sasines. These are held in the National Archives of Scotland. In the absence of a will this ought to be the easiest way to find out, but you will need to get an Edinburgh-based searcher unless you can go to Edinburgh yourself.
The other method is to look in the valuation rolls. These list each property with the name of the proprietor, the tenant and the occupier, insofar as they are not one and the same person, and the rateable value of the property. Moray Local Heritage Centre has copies of the VRs for Banffshire from around 1930. However the lists are arranged in an arcane order, within parishes, so it could be quite a long job to find the right Deveronside (I would think there could be quite a few houses with the same name).
