Try Something like this
<system>
<fullname>Mame</fullname>
<name>mame</name>
<path>/userdata/roms/mame</path>
<extension>.zip .ZIP</extension>
<command>python /usr/lib/python2.7/site-packages/configgen/emulatorlauncher.py %CONTROLLERSCONFIG% -system %SYSTEM% -rom %ROM%</command>
<platform>arcade</platform>
<theme>mame</theme>
<emulators>
<emulator name="libretro">
<cores>
<core>mame</core>
<core>mame0139</core>
<core>mame0174</core>
<core>mame078</core>
<core>mame078plus</core>
</cores>
</emulator>
</emulators>
</system>
<system>
<fullname>Mame2003</fullname>
<name>mame2003</name>
<path>/userdata/roms/mame</path>
<extension>.zip .ZIP</extension>
<command>python /usr/lib/python2.7/site-packages/configgen/emulatorlauncher.py %CONTROLLERSCONFIG% -system %SYSTEM% -rom %ROM%</command>
<platform>arcade</platform>
<theme>mame</theme>
<emulators>
<emulator name="libretro">
<cores>
<core>mame078</core>
</cores>
</emulator>
</emulators>
</system>
<system>
<fullname>Mame2016</fullname>
<name>mame2016</name>
<path>/userdata/roms/mame</path>
<extension>.zip .ZIP</extension>
<command>python /usr/lib/python2.7/site-packages/configgen/emulatorlauncher.py %CONTROLLERSCONFIG% -system %SYSTEM% -rom %ROM%</command>
<platform>arcade</platform>
<theme>mame</theme>
<emulators>
<emulator name="libretro">
<cores>
<core>mame</core>
<core>mame0139</core>
<core>mame0174</core>
<core>mame078</core>
<core>mame078plus</core>
</cores>
</emulator>
</emulators>
</system>
<system>
<fullname>MAMEFBA</fullname>
<name>mamefba</name>
<path>/userdata/roms/mame</path>
<extension>.7z .7Z .fba .FBA .zip .ZIP</extension>
<command>python /usr/lib/python2.7/site-packages/configgen/emulatorlauncher.py %CONTROLLERSCONFIG% -system %SYSTEM% -rom %ROM%</command>
<platform>arcade</platform>
<theme>fba</theme>
<emulators>
<emulator name="libretro">
<cores>
<core>fbneo</core>
</cores>
</emulator>
</emulators>
</system>