To prove that your wife has a good job in China, good income, and others, and she will be tempory to vist you, and she will be sure to go back to China until she get GC. Also, it is better to let a company invite her to do business. So, she may get B visa. However, once she get it, you also need to let her back to China. Otherwise, she may not get GC for some reasons until you are citizenship.