Your best bet against the flu is to receive the flu vaccine (this year, it contains the 2009 pandemic H1N1 strain, seasonal H3N2 strain, and one of the B lineages, Yamagata IIRC). If you start showing symptoms of flu, you should optimally start taking an antiviral within 48 hours.
Anything "homeopathic" is a scam. Those "homeopathic remedies" are so diluted that the chance of finding a molecule of active ingredient is orders of magnitude less than the chance of winning the Mega Millions or Powerball. People buying those are basically paying premium prices for a small bottle of water or buffer.