This reaction can proceed at very high temperatures (2000 - 3000 K).
At temperature above 1000 K you can expect decomposition of Na2CO3 and CH4
Na2CO3 = Na2O + CO2
and CH4 = C + 2H2
At about 1000 K and above carbon dioxide cannot exist at the presence of carbon or hydrogen
so reactions
CO2 + C = 2CO
and
CO2 + H2 = CO + H2O
can be expected
Moreover Na2O can react with Al2O3 forming NaAlO2
Finally, depending on ratio of substances and temperature used you can expect:
below 1000 K (approximately) - no reaction or slight decomposition of methane
about 1500 K - CO, H2O and NaAlO2,
at much excess of methane reduction CO by hydrogen
CO + H2 = C + H2O
and at temperature of order 2500 K and excess of methane you can expect reduction of NaAlO2 by hydrogen followed by reaction Al and Na2O with formation Al3C4 and Na4C