ainsi son voison, avait pour industrie d'exploiter la charité des autres et d'utiliser ses filles comme messagers = She exploited the charity of others and used her daughters as messengers. Are you referring to Monsieur Thénardier and Madame Thenardier , the corrupt innkeeper and his wife? They have five children: two daughters (Éponine and Azelma) and three sons (Gavroche and two unnamed younger sons). They take in Cosette in her early years, mistreating and abusing her.

'avoir pour industrie' is a good way to say in French ' having as a business 'so and so.. Ca veut dire c'est devenu son activité économique. " Hence his neighbor made a business out of using and exploiting people's charity and used thereby his girls as messengers." If you have more context to add to this passage ,it will help to explain to you in details. If you have read the book or you are in the process of reading it you will know exactly what those girls were doing.It is not so clear here and I didn't read this book to tell you!

Yes it sounds kind of weird ,(I guess coz it comes from an old book ) Anyway, I would understand this like :" thus his/her neighbor used to profit from people charity as a manufacture ( like having the hang of a mass using of this charity) and to use her daughers as messengers. hope it helps !

i think was a poetic word for saying that his way for live was to use his daughter to excite pity of people! bye!