The unknown message...

When Nicole saw her that Ava was not replying anything she eyed at Ashton to explain her what's actually going on. 

"Ace was not with her last night and because of that she had to stay with Aunt Melanie. But what bothers her that she doesn't know when he is gonna come back because she is feeling very insecure about the girl that had messaged him that night. What if that girl is there in his shooting location, and that's the reason she is slightly upset now." Ashton explained and Nicole just took her time to understand the situation well.