The 1840 edition introduced the singular “mother of abomination”. This change occurred only here in 1 Nephi 14:10, so it is undoubtedly a typo rather than the result of Joseph Smith’s editing. In three other places (all in this chapter), the text reads “mother of abominations”—and without any variation, even in the 1840 edition.
Summary: Maintain the plural “mother of abominations” wherever it occurs (four times, all in 1 Nephi 14).