exactly as jillius says, why should the social services pay to put roof over your head? your mum will also lose any council taz discount she may be receiving for low occupancy
At the other end of the move, do you realise that to rent your property out you will have to get permission from your mortgage lender? They may agree it with no trouble OR they may increase your interest rates. Also you will have to notify the insurers that you are not living in the property yourselves.
You may also be liable for tax on any profit you make over and above the mortgage payments.
The best solution may be to get a buy to let mortgage on the property and take out a mortgage that releases any equity the flat carries.
Speak to an independant financial advisor