It takes you at least 90 seconds to be able to siege two tanks, given that the rush distance is usually lower than that and your opponent is already going for a push that would most likely be too late.
Marauders are the right units against tanks, combined with Stim Pack.
Marauders do +10 damage against Armored units. Combined with effective Stimpack usage, they have almost the same DPS against armored units as Siege Tanks. Consider that supply-wise you can have 3 Marauders for every 2 Tanks, this advantage is escalated.
At 125HP, each Marauder can soak up 3 shots from a Tank's siege cannon. They also move faster than any Mech unit, allowing them to establish superior concaves on grouped Tanks.
But, there are also Marines so you need to bring your Hellions back to aid your Marauders, as well as your Medivacs to heal your Marauders. If you didn't lose them in your harass, which you always should try to do, you can take them home before he comes given that they are faster units.
The only problem left here is scouting, given that you can only create 2 Marauders a minute from one Barracks you can't start them once you see the tanks but you rather have to anticipate for it. One option is to integrate Marauders into your build order, and perhaps an hidden expo once you have the money to a location he can't easily access. But, that only works if you managed to take his production out, so it gets a matter of being able to destroy his remaining units...
Indications of an early factory are:
- Scouting with a worker reveals Gas made before Barracks.
- Scouting with a worker reveals no second Barracks when you stay till the first marine pops out.
- Scouting with a single Tier unit reveals no Marauders and a not too big Marine army.
- Your second scan reveals a Factory or a Tank.
- He does not come with a 3 Rax Timing Stim Push (~6:00) but rather for a push after 7:30.
If you have the resources for it, landing Vikings might help both defensively (against the push) as offensively (against his base), you can always be nasty and hide a building in an area he can't get to anyway so you can freely destroy his base. Your vikings can also become handy to chase him down if he decides to fly away, if you didn't build them you could see a draw...
So, going Marauders Hellions Vikings with some Medivacs first for the drop might be viable to do.
It's vulnerable to Banshees though, so sufficient scouting once gain is important...