EPC format belongs to Jill game. I am afraid the you have confused the file formats because it is not possible to convert the file to ePUB. On the other hand you can convert the file (EPS format which I believe you're having) to ePUB using any converter available.
For this purpose you can use Calibre. Import the files into this program then use Convert e-books. Make sure to select the output file to ePUB format.