Like you said, Geet's parents are spineless and wouldn't dare to make a move towards her without Darji's permission.
They would never have come to the wedding despite Maan's pleading.Which is why it's fitting that Darji came...he was after all the root cause of Geet's problems, including his upbringing of Brij.So by coming to the wedding and abjectly repenting for his deeds, gave complete justication to Geet's actions. He realised that she was right all along and he was wrong.The only issue I have with the Cvs is that since Darji came, the rest of the family should have come too, especially the parents.....even if they had to bring in new faces.