The person who created the database specified an additional filegroup to hold the application data (.NDF) and to keep it separate from the Primary filegroup (.MDF). This is actually good practice and can help restoration in the event of corruption.
There are also several transaction log files. I expect the additional ones have been set up in the past to overcome space issues on your c: partition. I'd consolidate these into one file and move it to a different partition to your data files - one with an appropriate amount of space. You can do this by shrinking the transaction log to its smallest size, deleting the additional log files and then move the one remaining log file by detaching, copying and reattaching.
To ensure your log file doesn't grow too large make sure you have the correct recovery model set. If you're using the fully logged recovery mode remember to schedule regular transaction log backups.
I'd also recommend setting an appropriate initial size and growth rate for the log file (rather than the 1MB, 10% defaults). E.G. 1GB initial size, growing by 512MB.