Alfrey is next summer.
Ellison can absolutely play safety, but he's on the small side. He's probably better suited for nickel or corner.
Udo has all the raw tools to play safety, but his football inexperience isn't ideal for safety. He's supposedly being groomed as a linebacker.
Brown is a good enough athlete, but I think the coaches want him on offense.
I suspect the coaches will look at the JC ranks again for another safety.