Why didn't the woman ask you directly?
(As a retired high school teacher I'm suspicious).
Could it be the son wants to do something and doesn't want his mom to know what he is doing so he'll use your network?
In any case, I'd say no both to the son and the mother. There are enough hotspots to send emails in distant countries with no cost except perhaps buying a cup of coffee to sip while using the free hotspot. If she doesn't want to spend the money for the cost of a cup of coffee, she can probably access free hotspots in parking lots of places with wifi. (Even one of our grocery stores has free wifi).
(As a retired high school teacher I'm suspicious).
Could it be the son wants to do something and doesn't want his mom to know what he is doing so he'll use your network?
In any case, I'd say no both to the son and the mother. There are enough hotspots to send emails in distant countries with no cost except perhaps buying a cup of coffee to sip while using the free hotspot. If she doesn't want to spend the money for the cost of a cup of coffee, she can probably access free hotspots in parking lots of places with wifi. (Even one of our grocery stores has free wifi).