I will say mohna played very well , there is a saying
" Ek teer se do sikhar "
First by help of saavi mohna released dilruba & send her behind Piya 2 trap her in RC.
Second when dilruba was no use of her , she joined hands with family 2 get rid off her
She won ansh's trust by helping him by making dilruba dance
That's why she was dancing so happily today
as she is sure if RC get breaked by dilruba's dancing then also Piya will not return coz she was trapped in RC on Poornima night , person inside RC disappear.
Her happiness was reflecting on her face
👏
But little does mohna know that her happiness is short lived as Piya was already out of d house, so Piya dint disappeared , will be returning back 2 RH
This will be a shocking moment 4 mohna for sure.