I have a Small Bus LLC. in USVI and the name is trademarked registered is it legal for a US Bus. to use the name to advertise online and their website

The answer is "it depends." Assuming by "registered" you mean that it is registered with the U.S. Patent and Trademark Office as a trademark, it is possible that the use by the online business is infringing. Whether or not it is infringing depends on a number of factual matters as to which you provide insufficient information, including whether the online business is competing with respect to the goods and services for which registration was granted. Our office practices in this area. If we can help you on a fee-for-service basis, please feel free to contact us.