There is Terminal-e-Jonub metro station entrance in the terminal, You have to get yourself to the nearest subway station to Hi Tehran hostel which is Haft-e-tir station on redline. So, there is no need to change the metro line because Terminal-e-jonub metro station is on red line also. Thus, after entering the station you should take Toward Tajrish trains. Get off at Haft-e-tir station. Take a look at from metro to hostel section for finding the rest of your path to our hostel.
You should go to Ghaem-Magham street which is just steps away from terminal entrance. Take one of the commute taxis to Haft-e-Tir station. It costs you about 2000 Toman per person. Ask the driver to help you in finding Mofateh street. Mofateh street is on the other side of square. So, be careful when crossing the street or use the pedestrian overpass. On moffaeh street go straight down and find Shimi alley or mofateh metro entrance. Now you are in Haft-e-tir metro station . Here is the rest of your way. From metro to hostel
Go to Azadi metro station, Take yellow line trains toward Kolahduz, and leave the train at Imam Khomeini station. Change the line to the red line and go to toward Tajrish direction of station. Get off from toward Tajrish train at Haft-e-Tir metro station and leave the station from Mofateh St. exit. Take a look at from metro to hostel section for finding the rest of your path to our hostel.