How can one deal with a childhood friend who has strayed far from religion and started frequenting bars with her brother, while the questioner is trying to be religiously committed and wishes for the well-being of her dear friend?

To everyone who seeks to learn her religion and attain uprightness: We thank you and ask Allah to guide you.

As for your friend: supplicate for her guidance and continue to advise her with wisdom, as long as you hope for her rectification. But if you predominantly believe that advice will be of no benefit, or you fear harm upon yourself, then leave her; in accordance with His, the Almighty's, saying: "So remind, if the reminder should benefit."