A: Hosting a shower is a gift in itself, and no other gift is required. As the host, you've accepted a responsibility that will likely take weeks, if not months, to carry out. You offer your home (or rent or borrow an appropriate location), select and send out invitations, plan the menu—and that's all before the event even takes place!
To avoid being empty-handed when it comes time for the bride to open presents, a smaller, token gift is always an option, or even a card for her to read. If you're invited to another shower for her beyond the one you're hosting, you don't need to bring a gift, regardless of which shower happens first. The most gracious brides make mention of the shower you are hosting when opening presents at her other shower, so that other guests will understand you are indeed giving a gift—just not one that will be opened.