Is there a good homeopathic remedy for teen with anxiety/aspergers?

No, none effective: Truly homeopathic "medications" are made by repeated dilutions, so that the ingredient is not really in the medication anymore (just the "essence" of it remains). That means there is no active ingredient left to cause any benefit. However, that also implies that the homeopathic "medicine" should be pretty harmless. Other non-homeopathic ingredients are often added and may have scents and flavors.

Biofeedback helps: Patients with Asperger syndrome who suffer from anxiety often benefit from hypnosis and biofeedback. Realize that there is no miracle cure for Asperger syndrome, however.