My 14 year old daughter has recurring bacterial vaginosis. She has taken flagy serveral times but the infection and foul odor always return, usually after her period. Are there any home remedies or vitamins we can try to eliminate this ongoing issue?

Period time. Make sure she takes full course of antibiotics. Change tampons frequently and keep the area clean. I don't think that there is any vitamin available for this. She is only 14 years old, and may need some instructions from you (mother) how to manage during periods.
Go natural! There are some great tricks to help her--if she uses tampons you can put some tea tree oil (2-3 drops) and coconut oil on the tampon and leave in overnight. Another great trick is as product called RePhresh. It's a homeopathic gel that you can get at most pharmacies. It re-establishes the natural pH of the vagina. A lot of girls will get this and eventually grow of it.
Difficult to treat. Home remedies are not considered effective & should not be used in lieu of medications known to be successful. In cases of resistant BV studies have shown the efficacy of TINIDAZOLE. Natural treatments do include: Praneem & Ginlac-V pessaries. Risk factors must also be controlled such as treatment of sexual partners, & suspension of vaginal douching, Vaginal clindamycin is also an option.