So, both excuse me and you are welcome ( giving answer for thanks ) are correct?
The hint is just "excuse me" and it accepts this answer, however the key words mode does not provide "excuse me" option, only "you are welcome".
It shows we are talking to that person (the second person) rather than taking about that person (3rd person). It's similar to using the 'vocative case' in many of the romance languages. Can someone tell us whether we must include يا ?