You can refer the following link to perform manual DR :-
Performing manual disaster recovery for Backup Exec 2014, 15 and 16
Or else, you can try mounting VHD's which will help you extact the data as you needed.
As a first and VERY important point (and as you say malware affected you) make sure that any disks with backups stored on them are write protcted and if possible work from copies when working out how to do the restore.
If you have VHDs (in an IMGxxxx folder) then the SBS server you backed up must have been virtualized within Hyper-V so the manual DR methods won't help as you have to do a virtual agent restore (which requires a Hyper-V host)
Basic steps would be
Create a Hyper-V host with enough disk space to hold your small business server
Create a Backup Exec server
Recreate an entry with Backup Exec for the disk storage and ensure that IMG older you have is then within that disk storage device
Inventory and catalog the device
Add the hyper-V host into Backup Exec
Create a redirect restore job of the VM to the host.