Why would " I am riding on the bus with my mother" be wrong? isnt that more accurate? going seems more vague, and easily replaceable with riding.
Well http://dictionary.cambridge.org/dictionary/english-polish/take says take here means jechać.
probably creators did not think about this translation, report.
because I go = is repeated action, better translated as "Jeżdżę", while I am going is right now, better translates to "Jadę"