1. She can lodge a criminal complaint agaisnt him and his parents for the acts of cruelty including dowry demand and harassment
2. She can very well file divorce petition and whether or not, if he is not giving her maintenance, then she can file a maintenance petition under section 125 c.p.c.
3. Let she take her kids with her, and his objections can be challenged in the court of law if he is filing a child custody case.
The Maintenance case will take years to get disposed, however she can get interim maintenance during the pendency of the main case. If he is refusing to pay maintenance even after court order, then you can initiate legal action for collection as per provisions of law.
The harassment aspect is top be taken care by keeping a constant vigil and making a complaint with the police if he indulges in it once again.