My mother spent the weekend in the hospital. She was diagnosed with a urinary tract infection, which was treated with antibiotics.
I took her home Sunday afternoon, but yesterday she was too weak to manage on her own. So she was checked back into the hospital (a room was waiting for her, so we didn't have to go through eight hours in the emergency room again).
Her spirits are fine, she was very apologetic about being a pest, and my guess is she'll make a full recovery a lot sooner than I will!