the minute arzoo or anyone

tries to think about the motive of alvira like when sahir was shot and alvira got a phone call she just excused herself and the minute arzoo thinks what kind of mother is alvira is the next scene we get is alvira giving vada pav to arzoo though it was for advertisdment and trying to gain sympathy from arzoo as well. Now we see that when acp asks arzoo about alvira the next scene i guess would be the fire scene so that everyone would see her as victim. Though its early to suspect her as culprit.