As far as I know it can be used for both "You are welcome" & "Excuse me". The developer only include "you are welcome" as the choice
no it cannot be used when greeting someone to your home because it technically does not mean 'you are welcome'
When thinking in English, it is a response to 'thank you' - which is 'you are welcome' in English, but not so in Arabic.
(thanking and the response to thanking are very unique to every language identity).