You need to phone the helpline and speak to a benefits adviser.
Your Mum is entitled to Attendance Allowance at least, if she isn't already claiming it.
I think you may also need advice on claiming Continuing Care via the NHS.
The Citizens Advice Bureau can also offer advice.
There is support out there but you have to track it down.
No one makes it easy or points you in the right direction until you ask, in my jaundiced opinion!
Good luck and stay strong..