The astrologer rescues himself from Guru Nayak's revenge by lying to him. Essentially, the astrologer uses his position as a social influencer to give his lie the weight of authority.
In the story, the astrologer presumably recognizes his arch nemesis when the latter approaches him. This is why the astrologer is so nervous. As for Guru Nayak, he fails to recognize his enemy from long ago, the man who once left him for dead.
Although the astrologer feels trapped, he remains calm. By leveraging Guru Nayak's desire for knowledge (and revenge), the astrologer is able to manipulate his enemy.
First, the astrologer tells Guru Nayak that the man who tried to kill him has died. In fact, the man has been dead for four months. The astrologer then tells Guru Nayak to return to his hometown in the north and to never venture south again. To reinforce his advice, the astrologer claims to see danger in store for Guru Nayak if he travels south again.
To mollify Guru Nayak, the astrologer also tells him that his killer died a presumably horrible death: he was crushed by a truck.
So, the astrologer rescues himself from Guru Nayak's revenge by using a combination of white lies to divert his enemy's focus.