Just a minor correction - that $160M is actually in USD, so they have more like $225M in AUD, which is the more fair comparison since the $100M market cap is also in AUD. Source: as per latest quarterly, default reporting currency is USD. OMN's got ~35% more cash than you thought they had.
By the way, did anyone catch today's AFR article? It's interesting that shareholder discontent with OMN's high cost base relative to its revenue is a common theme. I did some quick calculations using page 35 of the investor briefing slides and found that OMN spends approx A$500k per year on salaries and benefits for each of its 160 employees. This seems extraordinarily high - both the number of staff and the mean salary. Especially considering the company isn't generating much revenue. I wonder if there's scope to reduce both numbers significantly in the near term, thus reducing cash burn.
Another interesting tidbit out of the article was the comment from Scentre group saying they're in ongoing discussions with OMN regarding "future opportunties". I didn't even know OMN was targeting the Australian market. More potential upside for OMN there perhaps?