You should have an amount of money that you can access quickly. An emergency fund ensures that you do not have budget interruptions, because you will not be blind-sided by unforeseen expenses or an unforeseen reduction in income. A good safety net would be enough money to cover your current expenses for at least three months, but ideally, it should be six months.
The barest minimum you should have in your emergency fund should be an amount worth three months of your family expenses.