But i think tat arnav's mom nd khushi's (real) mom were frnds... may be khushi's mom knew tat arnav's father hd an illegal affair.. nd she told her frnd the truth.. Arnav's mom wud hv been devasted listening to all dis wud hv committed suicide.. nd his dad might hv been killed by his uncle nd may be framed it as suicide...
As garima is sister of khushi's mom she knws abt all this nd she was shocked to see dadi nd she hid..
And the stopwa dadi as stated by arnav earlier, looks oly frm her POV.. nd believes oly her son is innocent, nd was framed by khushi's mom(woh aurat)... as she lost her son may be she was emotionally disturbed nd she goes away to ashraam...