Once I learned the message from Jonah had been 'erased' (and couldn't be retrieved supposedly), I came to the realization NINA erased that last message from Jonah, hence her story about Rebecca handing her cell to NINA (the reason why NINA's prints were all over Rebecca's phone). Perhaps Jonah was trying to warn Rebecca? But Rebecca was already, for lack of a better word, dis-abled.
Yes, that's close to what I think, too. Dina had had a few hours to absorb the impact of what Max's injuries were, and that he would, IMO, never recover. I think Jonah knew Dina blamed Rebecca, and was on the warpath, planning to confront Rebecca. I don't think even Jonah thought Dina might actually kill Rebecca, but that there was a loud, angry confrontation coming from Dina to Rebecca. I think Rebecca had experienced Dina's stalking and anger before, and knew about her violence from the end of Dina and Jonah's marriage-- and probably was more than a little afraid of Dina. I think Jonah was calling to WARN Rebecca that Dina blamed her, and was headed her way.
I think Nina also knew Dina was headed to start an angry confrontation late at night with Rebecca, and Nina was on her way over to rein in Dina. To keep Dina from doing something angry and vindictive that she'd be arrested for, etc. I think the violent confrontation was already in progress when Nina arrived, and it was too late to stop Dina from attacking and hurting Rebecca-- who was likely still conscious when Nina arrived, IMO. At that point, they decided Rebecca had to be silenced, permanently, IMO.
I agree that it makes most sense that Nina handled Rebecca's phone, and erased the voice mail from Jonah. The story about handling Rebecca's phone in the car from the airport was just ridiculous-- another example of a convoluted explanation for a situation that didn't need ANY explanation. Like the "I never touched the gate" thing. They both sound like lies to any reasonable person, lies told to cover things after the fact.
Nina didn't indepently have a grudge or vendetta against Rebecca, IMO. She is just very loyal to her twin sister, in a fatally misguided way. So loyal, IMO, that she helped her sister murder Rebecca and try to cover it up and deflect attention away from Dina. That's what I think.