Become member of society and scrutinise accounts.
Get a CA friend to send queries on expenses. Maybe why 15 samosas were ordered when the meeting was for 5 people.
Question their conveyance expense
Tell them to prove that diesel was used only for generator and not siphoned off to fill their cars.
They will suspend your membership
Send a mail to registrar of societies and bankers alleging that accounts are not being presented when asked.
Catch them on small technical issues. Question why the auditor was paid X amount.
Ask them if GST is registered. If yes. Send a mail to GST department asking them to check ITC. This can be anonymous.
It will make life hell for them to answer all departments. They will finally come out clean. But mental harassment . Time. Effort.