I think she needs to make a decision sooner than that. She can’t keep bouncing between the two countries and not making the US her proper permanent home, at some point she’ll be at risk of losing her LPR status. What ties does she have to the US other than you? House, job, filing tax returns etc? As @OldUser asked, how much time has she spent in the US since getting her green card?
As for your brother, has somebody already petitioned him? Not sure who ‘and family’ is but if he’s married and he’s not been petitioned already there’s no way he’ll be moving in 10 years. It would be a lot longer, and the quickest route would be for your mother to petition him - but if he’s married she’d need to be a citizen first to do so.