It's a while since I've played, but I seem to recall there are sufficient bloodstones to unlock everything in the Homestead even when donating one to that awful reprehensible ingrate Frederick.
So from that reply, what you should do is up to you: I always end up healing him and then always end up feeling like a total mug for doing so because he's such a thoroughly unpleasant chap. But it doesn't appear to come at any long-term cost that I've noticed, whereas not gaining that point of forgiveness may tip the balance.
