I am filing forms I-130 and I-485 for my wife. I have a couple of questions regarding this. Can I file forms I-765 and I-131 with the application (she is in the US on H1B)? And if I can file I-765, what should be the "Eligibility Category" in question 20?
Yes, you can file forms I-765 and I-131 concurrently with the I-485 Adjustment of Status. Since you are filing the I-765 with a "normal" Adjustment of Status your Eligibility Category will be (c)(9) (see 7A in the instructions).