The point about the Earnshaws needing their mother to hang on for another three months relates to UK Inheritance Tax. No tax is payable on any gift given more than seven years before the giver dies. If however, the giver dies within seven years, tax can be applied retrospectively. There is a sliding scale, known as taper relief, so that if the giver dies six years after the gift (as here), the tax rate is 8% (from a maximum of 40%).
In the case of large transfers (eg a property), even after various allowances are taken into account, 8% can amount to a significant sum.