If you're out of data, it's likely something on your network used the data. Devices can use data without your knowing it. If you think someone may have accessed your wifi, change the password.
You can see what's currently connected and disconnected since the last time the HughesNet modem was plugged in here.
There are various apps/programs you can use to monitor the data usage on a particular device. Glasswire is very often recommended for Windows based computers, and they also have a version for Android devices. It's free. There's a paid version, but the free version is good enough. Some devices also have built in apps to show you how much data they've used.