Hi Greendeco13
The onus is always on the claimant to notify DWP of any changes to their income from other sources.
I am not sure what you are asking for, does the elderly lady still have an over payment outstanding? Is the overpayment disputed?
If the overpayment is disputed you could ask your local Welfare Rights Organisation for help or even your MP.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems