Son and wife not having the vaccination

I am presuming you have had your doses of the vaccine, in which case you do have a good measure of protection against them.
I wouldn't say too much about their refusal as you may find peer pressure will begin to work when other people, colleagues, friends, holiday places etc. exclude them.

YANBU. I honestly can’t understand why someone wouldn’t after all the world has been through.
My 7 year old has been begging for it!

No. IMO you're not being unreasonable. Stick with what's right for you. (I guess that DS & DiL won't seek to travel overseas!)

No you’re not being unreasonable. Just as they have made their decision based on what they feel comfortable with, you too should make your decision on that basis.

Having said that, and having been the world’s most cautious person up till now, I am feeling much more confident having had two doses.

Meeting outside for the Summer is good and hopefully we will get our booster in the Autumn and then you might feel confident enough to resume childcare for your granddaughter.

Easy does it ?

Is it that they have a manufacturer preference? That would be understandable.

No I don't think you are. Both mine were really excited to be getting the vaccination. I wonder why they don't want it.