"Then, I am going to bring her some."
Translation:Alors, je vais lui en apporter.
As an indirect object it can be both. I believe it's just when you're using stressed pronouns that it's elle: http://french.about.com/od/grammar/a/pronouns_stressed.htm
"En" is "some", both are Pronouns for something that would have been specified before. "En" means practically "(some of) them/this/these/that/...".
"Lui" stands for "her" and is an indirect Object Pronoun. Read here about the word order in sentences with Object Pronouns: http://french.about.com/od/grammar/a/objectpronouns_2.htm
Why "en apporter" & "quelque-uns"? Doesn't the "en" have the "quelque-uns" covered?!
When I did this question, the answer included both! Hence my query on it! Looking further up this discussion the answer stated here indeed doesn't include "quelque-uns"...
First of all, it would be "lui apporter". "L'apporter" implies direct object "la." As for the position of "en," it will always come right before the verb when it's required. See http://www.class.uh.edu/mcl/ta/vandermaliere/copiepronomsexplication.htm
That would be the position of «en» if there wasn't an infinitive, but when there is an infinitive, «en» immediately proceeds it (with some specific exceptions). Basically, it follows the same rules as placement of the direct or indirect object pronouns. As for what that sentence could possibly mean, you'd have to start by getting at what "J'en vais" would mean, and it's something like "I'm going away" or "I'm going about it". So, all together, it would be something like "I am going about it/going away to bring to her." Not really grammatical. Almost all the written examples of that structure are from French before 1900, so maybe at one time the rule was different.
The fact that « elle » isn't an indirect object pronoun in French. http://french.about.com/od/grammar/a/indirectobjects.htm