Bam
If this is a joint claim. even though she is not the primary claimant I believe there is still an obligation on her part to provide any financial information that the DWP request, failing to do so may result in their ESA payments being suspended.
How may properties do they have? If it is just your mothers and they live in it, then it should not be considered an asset for the purposes of ESA.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
