Hi there,
Firstly, your raw quant score is really good. It's out of 51. A 48 is pretty solid!
As for your undergraduate GPA, here's my opinion. Keep in mind, your particular situation is rather unique so others may disagree or have their own perspectives. There is no right answer here so it'll be up to you to figure out which makes the most sense to you.
Since you got an EE degree from Stanford, that cuts you a little slack. Engineering, and especially more difficult engineering such as EE, gets some forgiveness when it comes to GPAs. Not a large amount, but enough to be important to note. Additionally, Stanford gets you some brownie points too. The real issue isn't your raw GPA, the issue is your grade variability. An A to D spread across similar level courses within a quarter is going to raise some eyebrows because it's a curious case.
Honestly, I wouldn't address it in your optional essay. It might come up in an interview and I think at that point you can be candid about your reasoning. But if you bring it up in an optional essay, you're calling attention to it without a significantly compelling reason. I'm not saying not going for help isn't a reason, it just doesn't quite qualify in the tier you need it to.
Not to mention, you have an amazing GMAT and a strong grad GPA. So not only do you have some strong numbers, but you also have 3 data points where most have 2. That dilutes the importance of your undergrad GPA.
Let me know if you have any questions - I'm happy to help!
Bhavik
