My brother’s wife has filed a case against him, me and my wife under Section 498A. Can we fight this legal action? Are there any ways we can challenge the case?

Yes, you can fight this legal action. You can challenge the case by demonstrating that the allegations are false, that there was no cruelty or harassment, and that the case is based on malice or motivated by other factors. You should consult a lawyer to discuss your specific circumstances and legal options.