Christmas and my mum-in-law

Our usually Christmas plans of a big family gathering aren’t happening this year because of Covid. My Mum-in-law has 4 grown up children, some with children themselves and some without.
My mum-in-law lives on her own and the rules in our area allow her to join 1 families bubble. She doesn’t want to join any families that have children because they are at school and she is worried about catching Covid.
So I suggested to my husband, we go and visit her on Christmas day and cook etc.
When we phoned her to ask if she would like to do that, at first she thought we were inviting her to come and stay and she sounded happy. However, when we said we would come to her for the day, she wasn’t happy.

Now I feel uncomfortable, because I want her to be happy, but I also want to be happy.
Going for a day is perfect for us but having visitors at our place isn’t ideal for many reasons and it wouldn’t make me happy.

I am used to making other people happy and go out of my way to do that. But with this situation, spending a day together is the most I can do without seriously draining myself.

Any advice would be great