I've been gone all day, literally, until just a little while ago. I'm sorry that I wasn't here to respond to your inquiry earlier. Yes, I believe that this should be the last dose.
Hopefully we won't be able to see any white at all in a day or so, but in any case I would let this dose be the last dose. We just need to watch her very carefully for a while to make sure the lesion doesn't start coming back.
I would also start easing back on the salt, with the next water change after this one. Go to 1/2 teaspoon per gallon for a couple of days, and then to 1/4 per gallon, and then to none.
Keep the temp under 77, preferably at 75F for a few more days as you back off the salinity.
I know you will be vigilant as you keep an eye on her for any changes, but I think she's out of the woods. As always, perfect parameters are vital.
I would go to a variety of good food for her now, some frozen blood worms, and good Betta food, and your usual good routine of a pea and fasting once a week.