She's not an apostle, a prophet, an evangelist, a pastor, or a teacher... so she is someone working in the ministry of helps which is where woman serv,
The "elect lady" is being taught by John in 2 John 9-10 how to protect the "children" of her assembly from those who might try to join the fellowship without having the proper doctrine of Christ. John was instructing this "elect lady" in protective pastoring activity of either receiving or rejecting members into the fellowship, depending on whether they came believing the doctrine of Christ or not . This "elect lady" was doing more than serving coffee and donuts in the entry hall (not to disparage this type of service.)
It is also quite simple to prove that there were women apostles (not the original twelve, of course) in the first century church by comparing a couple of texts. The signs of an apostle were "signs and wonders and mighty deeds" (2 Cor. 12:12). Speaking in tongues was a sign (1 Cor. 14:22). Women in the early church were prophesying and speaking in tongues at Pentecost (the Joel 2:28-32 prophecy of the Holy Spirit being poured out on all flesh in those days - daughters and handmaidens as well). Since women were performing the signs of an apostle, this means there were women apostles in those days.
Saul / Paul before his conversion was haling some of these women along with the men and throwing them all into prison. Saul / Paul would not have done that if the women had not been active participants in preaching the word. The OT had predicted that women would be preaching the word. As predicted in Psalms 68:11. "The Lord giveth the word:
the women that publish the tidings are a great host."
When scripture in 1 Corinthians 12:28 ranks the roles in the ministry in order of priority, it is "first apostles, secondarily prophets, thirdly teachers, after that miracles, then gifts of healings, helps, governments, diversities of tongues." We can prove from scripture that women were apostles (meaning "sent ones" - in addition to the original 12 Apostles), and also prophets (as the four prophetess daughters of Philip in Acts 21:9). If these primary roles were not forbidden to women in the early church, then none of the lesser ranked roles would have been either.