Called for interview after dropbox

I came to India to in Jan 2019 for vacation and was eligible for drop box to extend my H1b and spouse H4 visa. After submitting documents in drop box, a week later got an email saying to attend an interview, email just contains my passport number, now I am curious whether my spouse also need to attend for the interview along with me or is it just me. Both of our ceac status shows Visa is in Admin Processing.

Does anyone has similar experience ?

If it has only your passport number, then it is only for you. Your spouse can accompany you to be there as backup on the day of interview…if they say, she needs to be around, she can join as well…You can always call the customer service to get clarity, if you are in doubt.