So agree that going to her may be a good option. Maybe even show up with some Febreeze, a new Swiffer, and some rubber gloves and a work apron, and offer to help her clean her bedroom/kitchen/living room or whatever she needs help with most (I know when I'm depressed, the house shows it!).
I must also say, I wish I had a friend like you around. I've been in the throes of anxiety/depression with the holidays/my birthday coming up, and all the other stuff that's happened the last two years (I sound like a freaking country song!). The seeming isolation is the worst part of it - I have, and still do, feel like I'm all alone in this. Knowing I wasn't alone would be one of the best gifts I could get. :-)