First of all, that """best friend""" is so incredibly toxic, holy fucking shit. He's jealous of Shiori because he's in love with Akio and yikes he's acting so fucking awful. It's so obvious that being apart from his family is slowly killing Akio, yet he continues to encourage him to stay away from them and live alone. If he truly, honestly loved him, he would tell him to go back home. What an awful fucking person.
And the mom... I'm pretty sure she only got in contact with Shiori so she could bum off her ex's inheritance. If she made enough money of her own, she should be able to either 1) support the girls with food etcetera herself, and use the money she gets (I assume monthly) from Akio for new clothes, or 2) use the money she gets for food etcetera, and treat Maho from her own money. Especially now that she doesn't even need to pay rent anymore, which I would assume is a pretty penny in Tokyo. I don't trust her one fucking bit. If she quit her job and that's why she cannot afford anything anymore that's even worse. That means she genuinely just came back so she didn't have to work anymore, and with how extremely carefully Akio has been using the money left to them, I doubt they can afford to take care of another mouth.