Can you use the "Candle item card" with the "It Is Meant To Be" event card, in order to roll 5 dice instead of 4 to use later as the card describes?
No, you cannot.
If you draw an event card, roll 1 additional die (maximum of 8 dice) for that event's trait rolls.
It Is Meant To Be says:
You can choose instead to roll 4 dice and write down the result. [...]
The dice rolling for It Is Meant To Be is not a "trait roll".
A trait roll is one where you are rolling a number of dice equal to one of your traits (Speed, Might, Sanity, or Knowledge). "Roll 4 dice" is not making a trait roll.
From the rules:
Sometimes a card or room tile tells you to attempt a roll based on one of your explorer’s traits (Speed, Might, Sanity, or Knowledge). When that happens, roll as many dice as your explorer currently has in that trait. For example, if your explorer must attempt a Sanity roll, and she currently has a Sanity of 4, roll 4 dice and add the dots together to get the result. Whether you succeed or fail, the card or tile will tell you the results of your attempt.
This rule does not specifically define "trait roll", but it strongly implies that "trait roll" is either "sanity roll", "might roll", "speed roll", or "knowledge roll"; because it defines a "trait" as one of those 4 things.