She should ask the pastor.
Why is she in RCIA? That is usually the way non-Catholics enter the Church. Perhaps the pastor thought it necessary that she receive some instruction to better understand the Catholic faith her family walked away from. If that is the case, he can determine when she is ready.
Technically, she should be able to receive Communion after making a good confession (of all the serious sins she committed since her last good confession) and receiving absolution. This confession would, of course, include the sin of leaving the Catholic Church and joining another ecclesial community (if she did it freely and was not forced by her family to do so). Before receiving Communion she should also have a Catholic understanding of and faith in the Eucharist, and she should understand how Communion in the Catholic Church (Christ’s Real Presence) differs from communion in a Protestant ecclesial community.