Nabisco Holdings Corp., Parsippany, N.J., said net income for the 3rd quarter, excluding non-recurring expenses, increased 13% over a year ago to $80 million. Worldwide net sales of $2.24 billion were up 9%. Excluding the impact of restructuring, operating income for the quarter was $225 million, up 15%. Excluding the restructuring expenses in 1996 and an extraordinary item in 1995, net income for the first nine months was $223 million, up 13% on net sales of $6.41 billion, up 8%. The company said its Nabisco Biscuit Co. unit reported strong sales of Oreo, Ritz, Chips Ahoy! and the new Air Crisp line. It reported weaker sales for SnackWell's and Newtons.