Book Club Rescheduling?

You might be over reacting just a bit. You offered to host twice, and twice rescheduled on them. They may not be upset or mad or whatever, but may just not want to deal with the possibility that this next one will be rescheduled as well. They want to have the meeting! You said you don't know them very well, so maybe they are wondering how reliable you are, and just didn't want to risk having another "rescheduled event".

Go to the one tomorrow with a smile on your face, apologize ONCE for the rescheduling issues (with a laugh that "when it rains it pours" or whatever, and a promise that you "really aren't unreliable. Maybe in a few months you'll all be willing to risk letting me be host again.. chuckle chuckle" ). Then forget about it. Continue to participate in the group (if you enjoy it). They will get to know you over time. It probably isn't nearly as much of a big deal as you think anyway. But they just want to HAVE the meeting....without any further reschedules. Just go! Make your apology and be done with that aspect.
We've all been there... when it seems like one thing after another keeps you from doing what you planned....

Once you are better send the woman that hosted in your place a nice bouquet of flowers or bake her a cake or something super special.

She did you a HUGE favor. Of course if you are ill, you could not host, but I know it can be frustrating when the person that says they are hosting has plans or makes plans for that date..We all kept it open, why couldn't they? I always wonder if they could have thought about it before volunteering.. when the rest of us have all saved the date.. Not mad, just a bit put off.

But I do know things happen.. Just try to volunteer again and make sure you do not let anything interfere again..

Just be apologetic. Get lots of rest and get better soon.

Just be more insistent. "Since Sue had to take over for me this time, I can either have the next meeting at my house or we can go to a restaurant and I will buy appetizers."