Mum wants to see her mum. You'd like to see your mum. Don't present her with a bunch of things, just tell her you love her and don't want to see her potentially put herself at risk over the vaccine.

In the end though, if she wants to see her mum and that's the only way...

Heck, if my mum was still alive, I think I'd consider getting the vax to see her for what may be one last time.