LadyL, I neglected to say in my previous post that I hope you are doing and feeling much better soon, in all respects.
The only other thought I wanted to add is that it sounds unlikely that your friend knows the extent of your personal situation, and it isn't clear (to me) the exact nature of your friend's need, meaning - is he asking to stay at your place to save gas for his family's use of the generator and/or significant wait time for getting gas - or is his request due to some other matter, or less or more urgency.
If you or LordL will be speaking with friend today, can you/LordL share some detail of your medical matters/considerations, and explain to friend that you definitely do want to help him in a time of need, and you are also in a time of need, so want to explain needed considerations for your situation and that you are working to balance both? That may allow your friend to either re-evaluate his request, or explain the reason he is asking to stay so his need is clearer and easier to fully understand.