Question

What happens when methyl cyanide is reacted with lithium aluminium hydride?

Answer 1

Methyl isocyanide is reduced by lialh4 (aka LiAlH4, LAH) with the formation of dimethylamine as shown below.

Personally, I would not make dimethyl amine, I would buy it, it will be much less expensive that the cost of materials (MIC, LAH, and the solvent plus whatever it costs to isolate).

Industrially, it is made by a catalytic process at high temperature and pressure from methanol and ammonia.