What, if anything, to say to DM to ease her anxiety

[Clutterfreeintraining]

DM is late 70s and has pre-existing health conditions which are well managed with medication.

I've been over to check in on her throughout lockdown (in the garden) and my dsis has been shopping for her every week.
For the last few weeks she has been venturing to certain shops herself (garden centre, carpet shop, supermarkets) but dsis still gets the majority of her groceries. She's also had several tradespeople in to do some quite major, non-essential, home improvements over the last three months and more work due to start any day.
She's now panicking about lockdown easing further and being forced into situations she's not comfortable with. I've said she doesn't have to go to places she doesn't feel comfortable but it doesn't seem to lessen her worry.
We both attend a group and now that we can meet in larger numbers, it is starting up again. She's adamant she won't be going because it's too much of a risk - the numbers will be relatively low, we'll be outside and it will be very easy to keep 2m apart. I don't really understand her logic and do think spending time with the others from our group would do her good.
I'm not going to pressurise her to change her mind about coming but this is the second time in a week where she's worried about having to do something that isn't compulsory and yet she'll happily have a team of tradespeople inside her home.
Should I just leave her to it or try to help ease her worries?

Is she more worried about those situations because she feels her safety will depend on other people's behaviour, people who she can't just walk fully away from as in a shop, or be in a different room from as with the tradespeople?

It being easy to keep 2m apart is only relevant if people are actually going to try to do it. It's not easy to keep 2m apart if other people think it's all a bit unnecessary so don't try, if you don't have the option to just walk off completely. Or even if you can in theory just walk off, socially that would be awkward so that's not going to feel like a good solution either.

Would she feel more comfortable just dropping into the group for less than half an hour initially (making some excuse as to why), so if she feels it doesn't work her departure was planned in advance and it won't suddenly be awkward? Having a planned out can make any kind of anxiety-provoking thing easier to try, even if you end up never using the out.

Yes, maybe that's it about feeling able to walk away. Although, she's usually pretty good at saying what she wants/doesn't want and not worrying about it causing any awkwardness.
The group we meet with are the same dozen or so that we've known for many years and I believe will have taken and continue to take SD seriously.
She may well change her mind between now and then anyway