Well, of course he didn't attend.

Surfing randomly about the web, I scan Right Bias, and find a link to this story under the heading "Obama Skips Grandmother's Funeral."

Well, duh.  Attending funerals is Biden's job now.  Everyone knows that.  That's why both the VP candidates wore black for the debate: to show that they were qualified to attend funerals.  It's all spelled out in a footnote to the Twentieth Amendment, in which the VP's duty to preside over the Senate is abolished, and funeral duty established in its place.