(a) The amount of the family allowance must be sufficient for the maintenance of the decedent's surviving spouse, minor children, and adult incapacitated children for one year from the date of the decedent's death.
(b) The allowance must be fixed with regard to the facts or circumstances then existing and the facts and circumstances anticipated to exist during the first year after the decedent's death.
(c) The allowance may be paid in a lump sum or in installments, as ordered by the court.