Type C Short stay family visa for Ireland

[Corw]

Hi
I have a quick question , can anyone please help me understand .My mother in law received her short term visit family visa and that is valid 17 Jan to 16 April , is she only allow to stay in Ireland till 16 April , or dose these dates means that she has to travel by 16 April ?
Please answer

[Vorona]

It is a period during which she can travel to Ireland. It's not a permission to stay.
To let her in or refuse her entry, or decide how much time she will be allowed to stay will be decided by the Immigration officer.

[littlerr]

She can travel by that date and will be allowed to stay in the state for up to 3 months.