TBH you have left it rather late. If he is looking at maybe needing care in the near future, you should have protected your investment years ago. Despite the fact you paid the mortgage, the assest is his i presume. The authorities wil see it as him deliberately depriving himself of an assest in order to gain an advantage (IE someone else paying for his care, not him) I think you can give property and such away but if it is then needed to pay for care within 7 years, it can still be sold. You might want to consult a solicitor over this, which will rpobably be the best idea. If he is likely to srvive for a longer time, you might want to think abut IHT as well, as it must be galling to pay IHT on something you already paid for!.
You say his property might be "grabbed" but this is the wrong words - it is looked at that its just using his assets to pay for the care he needs (could be up to �1000 pw depending on what he choses) - as said before why should all of us pay for that in order that you become richer when he dies?