Is it possible to say "ela não está na sua casa" here?
Yup! correct too
Oh. Thanks, Paul. I was wondering why they didn't say "na sua casa." Is it always acceptable to omit the article? Or not? And why? Lol.
when you have "possessive+noun", you can omit the article. It's called possessive adjective.
Hm. So does that mean that you can omit the article any time except when the object is a pronoun?
Yes,when it works as a pronoun you need to add the article.