Please think about the following:
According to the Code of Ethics your therapist is NOT ALLOWED to accept a gift from a client or client’s family. The therapist faces sanctions upto and including loss of license. Mishloach Manos IS considered a gift, therefore if your therapist is a licensed professional and he accepts the gift it could ruin his/her professional life. Sending a Thank You card or a personalized bracha from you is no problem.