£0 remaining for a small double mattress

A single, isolated mum is a carer for both of her two children. Mum had suffered significant nerve damage after a traumatic labour and is in need of a small double mattress as her current one is old and doesn't provide the proper back support she needs. This mattress will enable mum to get the rest she needs to be able to continue caring for her family's needs. Although mum is in employment, her finances are stretched with the care needs of her family. Please could you help? Thank you.