Since epipen (epinephrine) can temporary relax the air way, can epipen (epinephrine) used for asthma attack in emergency situations when no asthma medication available?

Yes it can: Absolutely, it is life saving in case of emergency.

Yes: Theoretically yes, an Epinephrine shot would work, but the use of inhaled beta adrenergics (albuterol) is preferred.

Yes if severe: You can use an epi-pen in an emergent situation if you have severe difficulty.Getting air into your lungs, and/or you are unable to get emergency care quickly. It should be used if you have no other options.