According to Pope Innocent XII:
“Why do we in this feast carry candles?
Because the Gentiles dedicated the month of February to the infernal gods, and as at the beginning of it Pluto stole Proserpine, and her mother Ceres sought her in the night with lighted candles, so they, at the beginning of the month, walked about the city with lighted candles.
Because the holy fathers could not extirpate the custom, they ordained that Christians should carry about candles in honor of the Blessed Virgin; and thus what was done before in the honor of Ceres is now done in honor of the Blessed Virgin.”
https://books.google.com/books?id=VKwYAAAAIAAJ&pg=PA168&lpg=PA168&dq=Candlemas+Pope+Innocent+XII#v=onepage&q=Candlemas%20Pope%20Innocent%20XII&f=false