If you don't have problems with power supply, or don't need to run on batteries you don't need to worry about the 100mA consumption.
Otherwise, if you have power close to where you need to run your "monitor node", but no power "at" the "monitor node" the solution would look like:
┌────────────┐ ┌─────────┐ ┌──────────────┐
│monitor node│ >>>> RF >>>> │base node│───Serial───│PC/RPI/ESP8266│───WiFi/Ethernet───{ Internet }
│ (battery) │ 100s meters │ (mains) │ │ (mains) │ │
└────────────┘ └─────────┘ └──────────────┘ │
┌────────┐
│ server │
│ app/db │
└────────┘
On the example above you still can communicate to/from the Internet, you just need to have the base node working as a gateway to convert a simple RF message. Depending on the complexity you can do it on a ESP8266 and send the data using simple HTTP GETs/POSTS directly to the server.
I'm assuming you do have some sort of mains at the site for your base as you're considering using WiFi network - which is very likely to be connected on mains 
Btw, for how long and how often do you need to collect the information? Depending on that you might still get away with an ESP8266