Help with Activity Monitor and excessive data usage

Hello,

I have recently noticed my MacBook pro (with macOS Mojave), is using huge amounts of data, without me actively downloading anything. I use my computer for emails, and safari browsing... and Ive just being on these for half an hour is showing over 1.3GB of data. I have no idea what could be using so much data.

I have opened my activity monitor, and I have downloaded Bandwidth+ to see the data usage. I can't make head nor tail of the Activity Monitor... and nothing seems to be using an excessive amount of data.... is anyone able to decipher this for me? I don't know what mDNSResponder is.. or Spotlight Networking?

My Safari Networking seems to be the highest, but this appears to grow even without Safari being open.

Could it be a virus or something? Should I uninstall something which is working in the background?

Would LOVE some help from someone who can advise. I have a screenshot here of my Activity Monitor.

Thank you in advance.