«أَمَّكُمْ دُونَ الْأَنَامِ طُرًّا»
He came to you in particular, rather than to all the other people.
Ammakum comes from a verb meaning to head toward or seek someone; it does not refer to “mother” here. Al-anām refers to people or creatures, and ṭurran means all together.
The visitor flatters his hosts by stressing that he singled them out for help. His request works through courtesy as well as need.