Surasa was a nagjanani ie ,mother of all the snakes,Kadru,surasa was also wife of Rishi Kashyap.She was daughter of Daksh Prajapati.To test Hanuman,his strength and intelligence ,Devatas had sent Surasa with a boon that whatever she wishes ,let that be in her mouth. Surasa wished for Hanuman ,he went inside her mouth and came out even before she closed it.
Thus Hanuman kept the words of Devatas and did not stop the mission as well .Mission was of God ,Devatas are his devotees, Hanuman,did show his grace on the devotees and their words even as his mission did not get affected,showing his extreme intellect.
Mainak,represented desire for wealth ,Surasa represents jivhachapalya( cravings for tasty food) ,it is important to overcome this craving ,[Bhagvat says conquering rasanendiriya leads to conquering everything],on a spiritual mission.
krishnarpana
