By default there is no hack file in b2evolution. Typically, this file is add when you install a hack.

So how can I install a hack? [url=http://wonderwinds.com/hackblog.php/2005/08/24/yaash_banning_ips_in_your_back_office]This hack[/url].

You create that file. Use any plain text editor and tell it "save as", type 'hacks.php' into the filename box, find and open the conf folder, then click save. b2evolution doesn't have it so that they will never over-write yours when you upgrade. BTW I think you will need to upgrade to use that one. Just found out from another forum question that my rechecker hack doesn't work in v10. I don't hack or test hacks in older versions even though for a long time after v12 came out I was still on v10.