Pre-ordering the iPhone 6s Plus at t-mobile but?

I don't know which plan to get. I'm getting a phone for my mom and I but I chose the 10GB family plan which will be $162.60/month is this a good deal for 2 phones?

It depends on how much you use data. If you have home Wi-Fi and use Wi-Fi on your phones most of the time, then you won't need so much data. But if you use your phones away from home A LOT, then the more data you will need. 10GB is a good amount of data too so.