Wow. Congrats on your admits! Fantastic job running a non-profit! That can be tough so kudos!
Amazing job on the GMAT by the way
I will tackle the easy topic first.
I would say that getting a dual degree can be both rewarding and tricky. When I say tricky, I mean that you will spend an extra semester at school (is that summer and fall?) and graduate out of the traditional MBA recruiting cycle. I personally don't think you need an MPH. It sounds like you are passionate about this field and that's great. For most people who are not considering a teaching career or stint, I would say a second degree is usually not that useful since often their background and resume already have Healthcare all over them. However, you did mention potentially teaching so that may come handy but for recruiting to consulting and PE, VC, type of things, it won't be a deciding factor. Consider the costs and opportunities I guess 😇
About Full Ride at Haas vs. GSB - it is only the VC that would add from a career standpoint. You do get better and stronger access. You can call VC's and get some time or at least get them to reply to your linked in messages. I have known only a handful of VC folks who went to Stanford but they were super helpful to alums as long as they were genuinely interested and engaging as opposed to needy and demanding
but the other side of things is how much do you want to get out of your experience and classmates. Your Stanford classmates will be a huge boost in caliber and diversity vs. Haas. You will get challenged more, you will have a stronger network and exposed to a very elite group. Sometimes it can be great and sometimes it can be intimidating. How important is this side? What value will MBA be bringing for you?
If you are thinking of working in consulting or a healthcare field then both programs will get you the needed checkmark and your experience rather than the particular degree will be. There are networking, opportunities, etc that are greater and better and juicier at Stanford but Bain won't hire just due to Stanford. They will interview you or not with both credentials.
Where I think you may be able to eek out value is if you start your own business, can you leverage the Stanford community and name to raise funding, or even fundraise for a non-profit. Which ecosystem would you be better suited or able to reach more like-minded people and individuals to help support your venture or non-profit? and is it worth $150K
Bottom line: I think if you are recruiting for "normal" post-MBA jobs, go to Haas. Much better value regardless of MPH. If you are considering teaching/hospital/healthcare jobs - research if MPH is going to be required or recommended to have and if yes, then Haas is a better fit. Finally, if you are planning to be upgrading your engagement, energy and pursue things such as VC and PE and hoping to be challenged and inspired (and sometimes disappointed) by your classmates and you can afford it (don't have undergrad debt) then Stanford would be worth paying for.
I know you are not that kind of person but for bragging rights and to really rub it in for your ex at a high school reunion, wearing a Stanford GSB sweatshirt can be very rewarding.