Let`s us say that a exchange got hacked, Would there be anyway to ban those bitcoins? like blacklist the stolen coins so they cannot be used on the network? I know about going back in time with consensus of the network to a earlier block or forking and using that new chain, but could you just not ban the stolen coins?  I mean make a way to do that?

Miners can,but will take a huge chunk of percentage of miners to agree to blocking the mining of a current transaction block where the moving of stolen bitcoins in.But mostlikely miners would not agree to such terms because they will lose some profits if they will not continue on running mining each block.