It’s never too early to begin planning for a reunion, especially one where you will be traveling out of the country. You may need either a passport or passport card to re-enter the U.S. If you have a passport/passport card you are good to go.
If you do not have these documents which are required for re-entry into the U.S. you must apply for the wallet size passport card, or if you prefer, a full passport. The passport card allows you to re-enter the U.S. at land borders and sea ports-of-entry. Additional information can be found here:
Passport Card (https://travel.state.gov/content/travel/en/passports/apply-renew-passport/card.html) or Passport (https://travel.state.gov/content/travel/en/passports/apply-renew-passport/how-to-apply.html); you can apply for one or both online.