Due to the ridiculous complexity in the HSE, it is unlikely that anyone in your local health centre has clinical responsibility for the public health nurses based there.
There will be a health centre manager who will be responsible for cleaning, security, phones, computers, non-medical supplies, etc. but this person will be clerical.
There will be doctors based there but they have no managerial function in relation to the nurses either.
Why not ask the nurses who their line-manager is? - probably a clinical nurse manager at a different location.