Dimona is 1700-1750km away from north Yemen, theoretically they can do it. But in practice the quality and capabilities of the missile (effectively a glorified SCUD derivative with low manufacturing / quality standards) will struggle to penetrate Israel's dense ABM/AD network. But no harm in trying and forcing them to worry about it and bleed Arrow-2/3 interceptor missiles
When Haj Qasem was unveiled (1400km range) they talked about increasing its range to 1800km, would be a good time for Iran to try to transfer slightly more advanced MRBMs to Yemen beyond the usual SCUD derivatives, although this is obviously not easy
It's not laughable at all, they launched hundreds of attacks. Of those 120 casualties it's probably 10-20 killed