Nowhere in the world is totally safe for a woman alone, sadly. However, my experience is that I was never totally alone when walking - it was rare when I couldn't see other pilgrims in front or behind. I walked in June, and felt comfortable.
This site is run by Ivar at in Santiago de Compostela.
This site participates in the Amazon Affiliate program, designed to provide a means for Ivar to earn fees by linking to Amazon