EasyBitcoin works
First try querying using curl in command prompt, if it works then go back to code and set user and password like you used in curl. I had the same error but its resolved
curl -u user:password -v -H "Content-Type: application/json" -d "{\"id\":0, \"method\":\"getinfo\",\"params\":[]}" http://127.0.0.1:port/
you can get the port by running multichain-cli chainname getinfo
Its a late response but may be it will help others.