Business tension or other tensions were going on. Something very bad- batwara or divorcing
Dadaji couldn't take it anymore and committed suicide but Alekh saw when he came upstairs to get Dadaji. Everyone in the house was shocked and to cover up the fact that Dadaji killed himself...
they lied and bribed the doctor to make fake reports.
In this scenario... no one actually killed Dadaji but everyone feels guilty.
what do you guys think?