from csv import writer

csvname="hoge.csv"
csvline=[a, b, c]

# only for the first time
if not os.path.exists(csvname):
　csvline_header=["a_value", "b_value", "c_value"]
　with open(csvname, 'a', newline='') as f:
　　writer_object = writer(f, lineterminator='\n')
　　writer_object.writerow(csvline_header)
　　f.close()

with open(csvname, 'a', newline='') as f:
　writer_object = writer(f, lineterminator='\n')
　writer_object.writerow(csvline)
　f.close()