The kidney problem that your mother is undergiong is a result of the damage caused by long standing uncontrolled BP. This damage is unfortunately irreversible, & the only help we can do to her kidney now, is to prevent further damage. This can be done by keeping a strict control over her BP.
Her liver disease too might have a role in worsening the kidney damage. She has to be cured of the Hepatitis C infection.
Follow the doctors advises strictly about the medicines to be taken, so that her BP henceforth stays in good control.