Pin worm and thread worm are the same thing.

They are not overly resilient parasites so washing in a regular wash and hanging things on the line or in the dryer should be enough to kill them (I don't think they would withstand the heat overly well).

Me and my DH were both wormed every 6 - 12 months by our parents when we were kids. They are a really common parasite - I think a lot of people probably don't know they have it until their bottoms start to itch.

Combantrine is fine for killing them and will easily do the job. I think the dosing instructions are different for different types of worms so as long as you read the packet and follow the instructions you will be fine.