Use curly quotes or single quotes:
C:\mongodb\bin\mongo.exe localhost:27017/BatGar --eval "var c=db.BatRegis.find({inspec:`No`}); while(c.hasNext()) printjson(c.next())"
or
C:\mongodb\bin\mongo.exe localhost:27017/BatGar --eval "var c=db.BatRegis.find({inspec'No'}); while(c.hasNext()) printjson(c.next())"