Covid-Throwaway. I think it’s both not okay but also understandable. By all means disinfect everything.
The short answer to this is I think is that she has missed you, and for longer than the Coronavirus has been going on. There is an opening to reconnect and she is emotionally driven to take it.
If she’s driven by some sort of “what if I never get to see my kids again” or “here’s a chance to connect emotionally we’ve never had before” feeling rather than just being bored I’d have a lot of compassion for that.
She maybe said she was bored rather than needing to connect because she isn’t good at recognising or articulating her feelings, or maybe she is shielding herself from a rejection that would cut deeper by making it sound like something mundane rather than something deeply emotional.
DH is in a slightly similar position - his dad died, his mum is vulnerable. He goes round once or twice a week with food, leaves it on the back door step and then speaks to his mum from the garden (well back) whilst she stands at either the kitchen door or window.
Dancing in the garden
People are feeling very disconnected and often like no-one is listening/responding at the moment, so someone wanting to connect with her daughters (especially one previously a bit emotionally estranged) at a time like this is understandable.
It is up to you whether you want that reconnection. If you do, maybe take a few steps back and try to think of a safer way (safer for you both) for you to reconnect. If you offered an alternative to her coming round rather than a refusal, it might make the situation more manageable.