has the insurance company demanded such requirements for an accident claim in writing?
His past illness have no relevance to accidental death,except incase of mental health.
if proved that your brother was mentally ill, the company may claim that the accident was due to that.
donot respond to the requirements made orally by the company. If you havenot received a written request for the requirements, send a letter to the divisional manager of the company,asking the present position of the case.
Donot immediately jump into legal proceedings which is time consuming and incurring expenses.
please use other channels of grievances like insurnace ombudsman etc.