I agree with the others. Food. There was nothing more frustrating than having to feed people while preparing for my mother's funeral.

A card

I also like the idea of essentials for the home.

Essentials for her, all the things you need on a daily basis, perhaps with a note about how important it is for her to remember to also take care of herself

Really, anything. Just showing up really helps. I was very grateful to the people who reached out to me, especially those I hadn't been close to recently.