Antonym of pall would be confidence according to the seeming meaning of the word.
Explanation:
The word pall can come to mean a lot of things. It has meant the cloth placed over a coffin in a funeral or the clouds covering the sky at some time. IT is associated with dark and gloom in general and this meaning is derived from that source.
The word can be associated with a sense of fatigue or losing energy in the way it comes to signify gloom and loss of life.
The opposite of that is confidence out of the options that are given here so it is the most probable antonym for the word.
