@muddleoffeelings
"It certainly wasn't to denigrate my DM, we are both obviously a bit emotional at the moment and nothing hurts more than disappointing your mum even when you are a grown woman in their late 30's."
That is understandable. These are crazy times, we're all figuring it out as we go along. And I expect we're all going to find that hindsight is 20/20 when we're able to look back.
And this is true for your mother as well. Now is not the time to be defensive, or worse, offensive. Your mother's heart is hurting. She needs reassurance, kind words, and love.
And it's more than okay to say to your mother, "I wish I knew how to have handled this better so you didn't feel hurt. If I had known, I would have. Everything is just too crazy right now. All the rules are opposite now. But it's not because I don't love you or appreciate you. I'm doing it because I love you and want to protect you. When this is all behind us, let's have a do-over."
Times are crazy for her too. She probably wishes she knew how to handle this situation better too, and may be feeling a little petty and sheepish on top of being just plain scared. You are right that a present a thing isn't the priority now. But you can give her the gift of love and support that she needs now -- no germs attached!