Putting Sapdata1/sapdata2 on C: is not good process. Anyway below are the things that you can do..
1. Clear the temp files in your C: (I doubt you will have much in there). Locations are
-> %temp% (or goto run and type it in every user)
-> C:\Windows\tmp(or temp) clear from there if possible - recheck before you do
-> Check every users desktop/docs if you have any unwanted data.
2. If you want to move the SAPDATAXX to other file-system as they are always suppose to grow.. shut down the DB>> Brtools >> 2. Space Management >> 6. Move data files
rest you will know as you proceed
3. Oraarch folder shift. Shut down the DB - change the initSID.ora to new point to new oraarch, start it.
4. Last but least - modify the Page-file size / reduce it? I won't prefer this any-time unless something is there.
Cheers,
TD