Cairns Business & Leisure Travel is a go to place for Torres Strait Islanders seeking compassionate fares to the Torres Strait. They are located in Cairns on Sheridan Street heading towards Toobruk Pools. 5-6/347-349 Sheridan St, Cairns.
Be sure to check online for the regular prices before you seek the compassionate fare as sometimes the normal rate may be cheaper and at least you will come prepared and can compare the prices.

Generally Qantas & Skytrans travel to Horn Island from Cairns, whilst smaller aircraft fly between the islands such as Skytrans, Torres Air and now the new highly recommended airline Hinterland Aviation is operating in Torres Strait.
Be sure you check the connecting flight times if you are using multiple airlines.
Skytrans does have history of cancelling flights sometimes at last minute and you could get stuck or miss a connecting flight.