I think somehow they will again pull Mandira behind this...may be she came to know the 'vasiyat' of Gujral...and as she is not getitng anything...she planned to kil him...so that atleast Virani's will be in trouble with the police case...ans down the heart she likes Karan a lot...as she could not bear the idea of Gujral planning to damage Karan...so so planned to kill him???
In the worst case Tanya might have killed him to rescue Bhoomi from his trap...untimately she will go to jail leaving her son/daughter with karan and Nandini.