Tough one..
If we consider b-d as passing notes, we end up with something like an Am7b5/G chord. It could be seen as a third inversion of the second degree with an Eb borrowed from the parallel key of G minor...
If we only take into account the dotted notes C-Eb, it could be seen as a second inversion of the fourth degree, again with an Eb borrowed from G minor. This would make it some kind of "minor plagal cadence" (iv - I).
I found some more info here: www.angelfire.com/fl4/moneychords/minorplagal.html