Here the parable in the beginning says that Kingdom of heaven is as this. We know that Jesus gave Peter the keys to the Kingdom (Matt 16:19), and Peter did opened the door of the kingdom in the day of Pentacost (Act 2). So here definitely he is referring to the disciples (or christian) in church. Some commentaries refers the last servant as those of old days who were afraid to be corrupted by the world that moved out of cities to live by themselves rather than being the salt and light of the world. I believe the talents can be all that we have recieved from God including the salvation and opportunities of sharing the salvation. And yes, we will be judged by our Master for our own deeds as Jesus talked about fruits and its tree to be relatable.
And I don't care what people or pastor says about "once saved always saved" theology which is taught nowadays. Bible clearly says sin will kill us. as it is written in Heb 10:26~27
"If we deliberately keep on sinning after we have received the knowledge of the truth, no sacrifice for sins is left, but only a fearful expectation of judgment and of raging fire that will consume the enemies of God."
Though we are not perfect and often sin time to time (or everyday even!!)
if we insist to have sinful "life-style" meaning justifying ourselves to sin as in Gal 5:19, we will be lost though we could be saved previously.
I believe this parable should be also studied with Parable of Ten Virgins, which starts with same heading.