If your parents both have other income of at least €12,700 per year each guaranteed for life (including State pensions) they do have the option of withdrawing all of their PRSA, with 75% of the fund being taxable at their appropriate rate.
They also have the option of buying an annuity (guaranteed pension for life) with the 75% (this would be the €55 per month income). Bear in mind that they can shop around for this annuity.
Or - they can invest the 75% of fund into an Approved Retirement Fund, from which they can withdraw at their own discretion.
If they don't have the €12,700 annual income from other sources, they're limited to 25% of fund tax free and annuity thereafter.
In either case, they do have the option to defer the withdrawal of their fund until markets recover, provided that these PRSAs were not AVC PRSAs.
If your parents were sold PRSAs that evidently have equity market exposure, were the risks and long-term nature of such a fund choice explained to them?