I'd go with your first guess. It's a bit formal, but that may not have been out of place here. In some contexts Madame would imply elder or married, but given the situation here I think it is appropriate. Madam can also mean the proprietress of a house of prostitution but it would not be the case in this context and probably wouldn't even come to mind. As for the difference between madame and madam would be undetectable in spoken English. Ma'ma would be totally innappropriate. I'm not sure what you intend by the apostrophe in the word, but it wouldn't be heard in the spoken version. Other than that, Mama means mother and is not used in this context in standard English. In versions of English where it would be used, its meaning is entirely inappropriate.