Hi @Meggle welcome to the family hub. 
I am a sibling too - my brother has severe learning disabilities and my parents are also in their 60s. It must be hard seeing the strain on your parents - financially and physically (with all the driving) - you just want them to be safe, financially secure and comfortable, and to be able to see your brother regularly. You may have already tried this - but you can search for extra grants and funding via www.turn2us.org.uk
I’m also wondering if there could be support from your brother’s local adult social care department for this - because it could be argued that it’s in his best interests to be able to see his parents regularly, and may come under his own social wellbeing needs?
You could contact Sibs to talk this through further, or the Mencap Learning Disability Helpline
Sibs - the UK charity for brothers and sisters of disabled children and adults
Contact - https://www.sibs.org.uk/contact/
Learning Disability Helpline
0808 808 1111
or email helpline@mencap.org.uk
Hope this helps and do keep in touch and let us know how it goes. There are a lot of siblings out there in your position - you’re not alone.
All the best,
Frances