The Nedarim source is one of the ones I did not learn on my own. The following information is quoted from the article Talmud Study by Women by R’ Yehudah Henkin.
“A source for permitting the teaching of Scripture to women, on the other hand, would seem to be the Mishnah in Nedarim 35b, ‘One whose vow prohibits him from receiving benefit from another, [the other] should not teach him Scripture, but teaches his [minor] sons (banav) and daughters Scripture.’ There is a variant reading that omits the words ‘and daughters,’ but Tosafot and Rosh in 36b wrote that even so, ‘banav’ in the plural means all his children, including daughters. This is also the opinion of Ran and the pseudo-Rashi commentary to Nedarim, and of Ri”tz as quoted in Shitah Mekubetzet.”
Since I haven’t learned this source myself, I can’t speak for which version is more common. You noted the one that omits “bnotav” as the “preponderant version” but R’ Henkin calls it a “variant reading”. Even so, as you see from what he wrote, it’s possible to use it as a support by interpreting “banav” as “children” rather than “sons”. In Hebrew, mixed groups are always referred to in the male form, so I don’t see a problem with this interpretation.