1. Because she will come here, I will meet her.
2. Because she comes here, I will meet her.
3. As she will come here, I will meet her.
4. As she comes here, I will meet her.
(Which one is grammatical?)
The first sounds like you both have a specific meeting planned, while the second seems like she habitually comes to the place, so you decide you will meet her there.
Both are better than the last two.
I hope this helps. Thanks for asking