Possible solution (if you have no ability to increase memory on that machine) is to add swap file.
sudo dd if=/dev/zero of=/swapfile bs=1024 count=524288
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
from https://github.com/pydata/pandas/issues/1880#issuecomment-9920484
This worked for me on smallest digital ocean machine