Can the molecule CH2(ONa)2 be stable?
The species you are proposing would be a methanediol dianion (CH2O22–) with two sodium cations “attached” to it in some way, depending on the nature of the solvent.

While methanediol can indeed readily form an anion, with a pKa of 13.3, I find no mention of the dianion or any measure (or prediction) of the second pKa of methanediol.