A jalsah was held for a boy who had completed hifz.

Answer

Even if there were no women present, then too, the jalsah was not permissible. It was a merrymaking concert of pride, show, and waste. (Takabbur, riya and israaf). On the basis of a false assumption of permissibility, the presence of women, regardless of them being upstairs or downstairs or in Hell's stairs, renders the jalsah impermissible.