Legal remedy against false criminal charges

My elder brother's wife was suffering from Cough & Cold. She was provided treatment as per my brother's ability. She undergone treatment in government hospital where sputum test was done for two days and tests were negative for TB. But she was still facing issues and later my brother started her treatment in Reputed private hospital where doctor's found the cough fluid is filled in her lungs and they asked to admit her immediately for treatment. My brother admitted her after 1 day and during treatment she expired. Doctors told her lungs collapsed during treatment and she died. My Brother informed everyone over phone regarding her death. But My elder brother's father in law come with her relatives and started beating my brother & Parents and lodged a case under IPC 304B after handing over to police. What legal remedy do I have?