Stroke/Dementia - Live in Carer - Financial Help

Nannytone

Contact social services and ask for an adult assessment.
She may be eligible to receive care air or even direct payments to pay for a person of her choice to help care for her.

This would include a financial assessment and if she has substantial savings May rule this out as an option

Fruitcake

I suggest you find a SOLLA agent (Society Of Later Life Advisors). These are government approved independent financial advisors, trained with additional qualifications specifically to help people who are elderly or retired etcetera. You should be able to get a free half hour or hour with one even if you decide not to use their services afterwards.

Mine helped me enormously with my late parents' situation and told me about things that could be claimed I had never heard of. Things that Social Services never told me about because some of the allowances came out of the local council's budget.

This doesn't preclude you from getting advice or help elsewhere, but sometimes knowing what allowances to ask for, and how to ask for it can help such as how to fill in forms. 
Some help agencies used to send someone to help people fill out forms so may be able to do that by 'phone/video/email. 

Groups such as Age UK and Age Concern are very good as well.

I also got tremendous help from my parent's GP surgery as well, but of course that might not be so easy at the moment.

Severe dementia would allow a claim for reduced council tax to the equivalent of a single person occupancy in the event that a carer has to live there permanently. I got my parent's GP to write a simple letter to the council tax department when I applied for this for my parents due to my Dad's dementia.