Hi Loosey, not sure who told you that mollasses prevents worms but I think maybe thats an old wives tale! Mollasess is pure cane sugar and is generally only used in animals diets as an appetite stimulant, and a good source of energy (think of kids that have too much sugar!). Plenty of people feed mollasses to horses (its in most horse mix feeds) and still follow a regular worming plan. The only way to ensure your piggies don't get worms is to follow a proper worming plan, your vet or an SQP from your local Agri Merchants could help you with this. I know we would all like are animals to have the most natural of diets, but nothing compares to drugs which have been put through proven clinical trials (sorry if that sounds a bit heavy but I am a trained SQP and have seen also the grusom results of worm infestation!)
Garlic however we all know is a fab herb, an antioxidant and improves general well being (is also said to be natural fly repellant!).
Hope this helps!