Why did we say here

Annen o odada

Can we say it without the O too?

Like this

Annen odada ??

In your sentence "o" (he, she, it) doesn't refer to the mom but it refers to a certain room.


Annen o odada.
Your mom is in that room.

The other version would have a different meaning.

Annen odada.
Your mom is in the room.

ohh,i see,tşk erdinc