Considering there will be care options in 4 months time it may be appropriate to shift the employees hours around temporarily to accommodate the sudden change. Its important to support them through this as they are valued employee. There may be the option of some time off but money seems to be an issue. Delegation of some of their tasks may be helpful.
Dismissal needs to be looked at as the next step. It would be advised to converse with HR for the correct procedure per company’s policy and to ensure that all implications will be avoided. All documentation must be presented as evidence for the decision.
The employee would need to be monitored more closely. It would be best to approach the employee and have a one-on –one meeting to try and understand their situation. There could be many reasons for the unsatisfactory performance