First of all, you need to go into scraper.py and change PIL to Image for resize to work. It’s one of the first couple lines of the script.
To scrape just one folder within your nes roms directory, I would suggest removing all other roms from the nes roms directory, scraping what you want to scrape, then putting them back in.
To only scrape nes directory, go:
cd RetroPie
cd supplementary
cd ES-scraper
sudo python scraper.py -w 275 -fix -p
If you want to scrape it manually (which is time consuming, but at least you know everything will be right), just add -m to the last line:
cd RetroPie
cd supplementary
cd ES-scraper
sudo python scraper.py -w 275 -fix -m -p