There is only one file type that uses the .MBF extension:
Microsoft Money Backup File
Backup file created by Microsoft Money, a program used to track personal and business-related finances; contains a backup of an .MNY file in either compressed or uncompressed format; used for compressing and backing up large MNY files into an archive; can be converted to .QIF files with the Microsoft Money software.
Microsoft discontinued sales of Microsoft Money in June 2009 then ended support for the software in January 2011.
Updated: January 7, 2021