Cannot remount /system partition even when rooted (Sony xperia M2)

I have a Sony xperia M2 D2303 with kitkat 4.4.4 and compilation number 18.3.1.C.1.17. I have rooted using KingRoot v4.9.5. I have checked that system is rooted using tools such as root checker. Now, I am trying to remount /system partition as RW but without succcess. I have googled and tried several solutions but nothing works for me: 1. Access to /sys/kernel/security/sony_ric and try to disable sony ric security using: echo 0 > enable problem is that sony_ric folder is empty, there is no "enable" file and I cannot create it as partition is RO (read-only). 2. Using ES file explorer or other file explorers as root I have tried to remount partition as RW but it fails. 3. Using ROM Toolbox pro, and then from terminal emulator I have tried some commands but all fail: **1st attempt:** su mount -o remount,rw /system **2nd attempt:** su system/bin/mount -o remount,rw /system **3rd attempt:** adb shell su mount -o rw,remount /system 4. I have tried to install busybox but it fails as well because I cannot write to /system partition. 5. I have tried the methods explained here but nothing works: Method A -> Cannot be applied in my case since sys/kernel/security/sony_ric/ is empty, no "enable" file exists. Method B -> Cannot install busybox since /system partition is read-only and I cannot make it rw using mount, etc... Method C -> I have not tried install init.d because I do not know if it a trusted method and whether it works in my device... Could someone confirm if it works? Method D -> Cannot be applied in my case, no "enable" file exists in sys/kernel/security/sony_ric/ So at this point I have no idea what to do... Any help will be highly appreciated.