As an outdoor grower, I can say without hesitation that cannabis can survive 57 degrees, no problem. They can usually survive freezing down to about 28 degrees(+ or - depending on humidity) before they start to take damage. Where I live, even during the summer it's common for temps to be lower than 57 at night, and even lower durring the spring/fall.
Personally, I feel that the temperature fluctuations that outdoor plants experience are part of the terroir of a growing region and is part of what makes outdoor cannabis interesting.
However, as others have said it is not optimal for max growth. Your nutrient uptake will slow to a halt during the cold periods and you will get better growth if you can get your nighttime temps up. I would be more concerned about your day time temps, 63 is too low.
They make tiny oil-filled radiating heaters,
https://www.staples.com/Optimus-H-6003-Portable-Mini-Oil-Filled-Radiator-Heater-White/product_1460592?ci_src=17588969&ci_sku=1460592&KPID=1460592 that might work for you.
Your plants will be fine at that temp at night, but they will grow bigger, faster, with warmer night temps, and your daytime temps are too low IMO.