There are multiple ones available to Houston and Texas. This is another that has not been posted yet. Houston housing is the one most people are approved through within 30 days. Let me know if you need help through the process.
Here are some websites where you can find a resourceful information about affordable housing.
Section 8 housing
Carlos your question is a bit broad. There are MANY programs available, so it really depends on what is going to be the best fit for your client. To learn more about the different programs, I highly recommend taking the Texas Affordable Housing Specialist Certification Class. You can find the days/times of classes on HAR course calendar. If you need help for a client quickly I would recommend connecting with a lender who is very familiar with DPA programs as there are multiple. The lender will be able to determine the best program for your client based on program qualifications. Also ask the lender if they are familiar with MCC Tax Credits. There are other grants that can be stacked on DPA like Neighborhood Lift, Bank of America Grants, and a few others. And other programs to look into like HUD & NACA.