The DMK may take a hard stand against the Congress and the UPA government if the CBI names Dayalu Ammal, one of the two wives of Tamil Nadu chief minister M Karunanidhi, in the second chargesheet as a beneficiary of the 2G spectrum scam. Dayalu Ammal is the mother of Karunanidhi's sons, MK Stalin and Union minister MK Alagiri. The second chargesheet is to be filed before OP Saini, special judge for the 2G case, here on Monday.