Which is correct? 'They are showing the tv program at the moment. ' or 'They are being shown the tv program at the moment.'
'They are being shown the TV program at the moment' is probably what you mean. 'Showing' in this context has a very specific meaning:
The film is showing at 9 pm
This means that at 9 pm you can watch the film at the cinema. Note that 'showing' in this context is not a gerund, and has a separate definition in the dictionary.