Malwarebytes, Windows Defender, or Bitdefender. 2. Remove the Malicious File
If the file belongs to a specific community mod (such as a King of Fighters character pack for M.U.G.E.N), do not use generic DLL sites. mai kf dll download link
Mai@KF.dll is widely identified by security analysis platforms as a malicious file, specifically a Trojan or Gen-Injector Malwarebytes, Windows Defender, or Bitdefender