Many BGOs conduct interviews in the candidate's home. Don't worry, they're not conducting inspection.
However, it makes it easier to speak to your parent(s) and answer any questions he/she/they may have.
Here's how to plan:
(1) Dress appropriately -- slacks and a collared shirt/sweater and shoes are fine. Nice jeans if that's the norm where you live. No sweats, shorts or bare feet. If it's your custom not to wear shoes in the home, well . . . consider doing it for the interview or at least wear nice socks.
(2) Decide the room in which you want to meet -- it's up to you. Living/dining/family room are all ok. You COULD offer water -- you do NOT need to. No need to offer food. Keep your dogs, cats, and tiny siblings away.
(3) See if your parents want to meet the BGO. If they do, they should do so at the beginning and/or end of the interview. Whatever they wear (provided it's decent) is fine -- they're not being interviewed. They should DEFINITELY excuse themselves if they are there at the beginning. The BGO wants to talk to you alone for at least part of the time. But if they have questions or concerns, this is the time to ask.
(4) As for questions -- it's up to the individual BGO. There is no script but there are general topics we're supposed to cover -- do you understand the honor concept, plebe summer, limited majors, etc. It's a conversation, not an inquisition.
(5) My personal view -- and it's only that -- is that it's nice to provide the BGO a copy of your "resume" (activities) and maybe your USNA essay. We do NOT have access to either and it helps us to remember you. Again, not a requirement but good to do if you can.
Good luck.