I think it's a little odd that your friend planned a birthday dinner party for her adult daughter and invited her OWN friend (or friends). If it was a family party, it would make a little more sense. But I think your friend may have overstepped and set the stage for an uncomfortable, too large production, especially, knowing her daughter is challenged with anxiety. Please understand how difficult mental illness is. A lot of "high-functioning" people may have the same outward appearances as yourself. But inside, they may be just barely holding it together. If this young woman really wanted a dinner party with friends, at 27, I think she would be planning it herself with her OWN friends. I don't blame her for canceling, even on short notice. Your friend may have been trying really hard (with good intentions) to make this work up until the last minute. The issue really is with the dynamic between your friend and her daughter. I wouldn't take it personally.