ANSWER:

You can say this dua in any sujood you want. 

Specifying the last sajda for making Duaa is not from the sunnah.

 

Please, can one say the following Du’a whilst in sujood, in the last rakah of Salah after he/she has finished saying ‘Subhana Rabbiyal ala’? Our Lord! Grant us good in this world and good in the hereafter, and save us from the chastisement of the fire. [2:201] Rabbana atina fid-dunya hasanatan wa fil ‘akhirati hasanatan waqina ‘adhaban-nar