Switching from MTB to road handlebars I have a gravel bike with an MTB setup. SRAM GX rear mech, SRAM XO shifter, 1x11 system, Shimano disc brakes. How would I go about replacing my flat handlebars with road bars?

Alternative 1
Get a hold of a Shimano 11-speed shifter, a brake lever and a Jtek Shiftmate to convert from Shimano ratio to SRAM.

Alternative 2
Get a hold of SRAM 11-speed road shifter and brake lever. Also need new hydraulic brakes which are not compatible.

Alternative 3
Get new mechanical disc brakes. Get SRAM shifters with mechanical levers. 

So what is the best alternative? Or do I have more options? 

And can I use SRAM GX rear mech with SRAM Apex or Rival shifters without a ratio adapter like Jtek Shiftmate? 

Much appreciated. Cheers!
You absolutely need SRAM shift/brake lever units. SRAM road shift/brake levers are compatible with their MTB derailleurs and come in a 1x11 version. 

Trying to mix Shimano and SRAM will just be a huge headache. I'm not even sure there is a shift cable pull converter for that.

Hydraulic vs mechanical calipers is up to you and your budget.

Something you should be aware of is that flat bar bike frames are typically longer than drop bar frames, because flat bars place the rider's hands closer to the head-tube than drop bar hoods or drops hand positions do. Check your bike's geometry to make sure you wont end up with too much reach.