No, it is not–and the reason is because we don't need to come to the angels, or to any other creature, to guide us. If we know Christ, we have everything we need in Him, and He alone is the one to whom we should come.
After all, when Jesus was taken into heaven after His resurrection, He was given His rightful place of authority at the right hand of God. Now, the Bible says, He intercedes for us–and He is all we need, because He loves us and we are His special concern. The Bible says, "Therefore he is able to save completely those who come to God through him, because he always lives to intercede for them" (Hebrews 7:25).
Yes, God has given us the unseen angels, who are "ministering spirits sent to serve those who will inherit salvation" (Hebrews 1:14). But we are not to worship them or pray to them. When the Apostle John fell down to worship the angel who had been sent to tell him about the future, the angel rebuked him and said, "Do not do it! ... Worship God!" (Revelation 22:9).
Let your niece know you appreciate her interest in spiritual things but urge her to turn to Christ, and to trust Him alone for her salvation. He alone is "the power of God and the wisdom of God" (1 Corinthians 1:24).