A meal in Temple Bar would make me consider the public car park on the West End of Temple bar which lies on the West side of Werburgh Street behind Jurys Hotel. Dealing with traffic and one way systems in order to cross the Quays to car parks like Jervis over on the Northside would be a non runner in my experience.
I would drop the elderly mother closer to the restaurant on Dame Street, drive west up Dame Street and then turn onto Werburgh Street. As you drive down the street, the car park is on the right hand or west side directly opposite the bus stop at the waste ground where people often get clamped. From there all of Temple Bar is 10 minutes walk away.
If you choose this car park; as Werburgh Street is a one way street I would caution you to drive slowly and look out for the car park entrance on the right hand side which is very sudden once you turn onto Werburgh Street. It appears reasonably priced too from what I remember with the overnight parking fee being capped at a maximum at weekends.
After collecting your vehicle you can drive around the block to enter Dame Street and pick up your relatives where you originally dropped them off.