In The Caller, why didn't Mary just go to her mom's home?

It doesn't matter even if she goes to her mom's place because Rose who calls her from the past could go ahead and kill her mom in the past if she doesn't answer her phone calls.

Yes she does have a real mom because we see her talk to her in the present and also Rose mentioning about her mom on the phone plus we see the photographs of them together in the movie with Rose standing in background all the time.

I think Rose is her mom. That's why she and Rose are together in the same house in two instances when Mary is a child, why you never see Mary's mom in the present, why only Rose and Mary's mom ever call her on that phone. Also, listen to the lyrics Mary sings as she puts her ex-husband in the grave; I think she's singing about "Mommy."

I think Rose and Mary's Mother are one in the same and I think the entire movie is a halucination of Mary's. I have watched it twice and am still not understanding it. What about John's parents in the diner when John introduced them to Mary....explain that one? And then when Mary goes back there on her own they tell her John is dead.