The short answer, as you have given no information about yourself, is that it could be either.
The long answer is that it’s probably a bit of both. Stress and anxiety leads to a degradation of the microbiota in your GI tract. As a result, any pre-existing anxiety issues could easily give candida a boost. However, once candida has taken hold, it will lead to a further degradation of your general health and will likely result in an increase in your anxiety. This is a massive over simplification of the possible relationship between your mental health and your microbiota, however it provides a useful example to show how the two elements can cause a feedback loop.
If you want to address your issues, it will have to be at both a nutritional and psychological level. Based on my own experience and having done a substantial amount of reading in the area, you will not attain a quiet mind just by eradicating candida. Moreover, it is unlikely that you would be successful in eradicating candida if you continue to subject your body to unnatural stress. However, it is also true that without the eradication of candida you will also find it difficult to address your anxiety issues.
It is a difficult malady to tackle. I recommend you get professional help, both from a decent nutritionist and a decent therapist.