Chase31's 50 starfire aquascape reef

[Chase31]

I had two chromis and two clowns along with a royalgramma my mom feeds the tank while I'm working. My royalgramma is still shy and doesn't go to the top during feeding but he still gets some and comes out, my chromis never ever miss a feeding. Now my mom called me the other day to say my female clown was chasing around the chromis till he hid in his little corner (his house). Now today my mom says she hasn't seen him all day or night and even when feeding he normally hides in between the rock wall and the glass. It's not like him to hide in the rocks or stray far from his buddy chromis. Would my clown have killed him? I feel like clowns couldn't be this territorial in a 55 g tank but her experience says otherwise. What do you guys think