I feel that one of the older male hopefully DM's father in law or Santu's nanaji tells DM to fix the domestic affairs. Dm is not so innocent him self. He knows the condition in the storeroom where santu lives is. He brought her home by merring her and she has not officially enter the house yet. Santu should have some room to live inthe house if not sharing Dm's room.
Father in law can come to Dm and put his two cent in to Dm's brain that eough is enogh and bring the wife in the house. He has to respect her publicly not just by the silent talk. As long as man of the house does not respect her ,no one will respect her.
Nanaji can also tell DM respectfully that Santu's respect and safety is Dm's responsibility and DM being the judge and jury of the town himself, he should be fair and just in his own house. Nanaji's grand has not committed any crime by merring DM, so she should not be punished for being DM's wife.