The bridal shower?should be hosted by a close friend of the bride or?the maid of honor. It is considered improper for a family member of the bride to host the shower since bridal showers are primarily a gift-giving event. However, family members can certainly pitch in and help in the planning. If the maid of honor is the bride's sister, as is common, it has become acceptable in most areas for her or a family member to host the shower. If it is a family only bridal shower having a family member host the shower would then be acceptable, too.
Traditionally, the maid of honor hosts the bridal shower, so if you want to help in planning, be sure to check with the maid of honor first she may already have one in the works.