In a loop Select All Players then Filter Select By Distance and put the Mob's location as the Location parameter
And then use Set Variable: Set To Distance and this will return a number, then you can check if the number is bigger or smaller than the distance you want
In a loop Select All Players then Filter Select By Distance and put the Mob's location as the Location parameter
And then use Set Variable: Set To Distance and this will return a number, then you can check if the number is bigger or smaller than the distance you want