Pollard Kangaroo approach is for the know private key range and for the best, within 125 bit range and of course since you have the Multibit wallet handy all you have to do is "Once you located the files, if you have access to an old multibit app on you computer you need to import the wallet and export the private keys to a new wallet. If you do not have a copy of Multibit, you can use OpenSSL together with your password to decrypt the files and recover the keys."