All you need is Marriage certificate and a few genuine photos of marriage. Make sure your wife wears saree and potey churas to the interview. If you're applying right after marriage they might look for mehendi also. Also these are the necessary documents Original I-797, Your employment verification. I don't think bank balance is necessary. I had negative bank balance when I brought my wife here. Showing income and paystub is sufficient should they care for it. I doubt they will. Basically give her a copy of all the documents that you used for getting your visa. But most important of all it's the proof of marriage like certificate, photos, wedding card, potey chura sindoor etc. These are the things that they will definitely ask for. Good luck and congrats.