Maybe. Generally, the pension plan rights of the ex-wife will terminate after the divorce, as to the right to a survivor pension but maybe not with regard to death benefits - other than monthly pension payments. Although, a Qualified Domestic Relations Order may be in place which determined that the prior wife would continue to be considered the surviving spouse for survivor benefits related to amounts earned while married. The new spouse, if married more than one year, and before the decedent began receiving his pension, may be entitled to a pre-retirement survivor annuity, or a portion of such, or a joint & survivor benefit. She should consult an ERISA attorney. My office handles such matters.
There are really two questions here:
1. Does the ex-wife have any rights to Decedent's pension plan?
2. What are the surviving wife's rights to Decedent's property?
Ex-Wife & Pension Plan
In general, as a result of a divorce, an ex-spouse is considered to have predeceased the other spouse for purposes of receiving any property as a result of the Decedent's death. See RCW 11.07.010 regarding nonprobate assets, such as a pension plan. This law, however, may be superseded by federal law --- ERISA --- depending on the nature of the property right.
Surviving Wife's Rights to Decedent's Property
See: Rights of Surviving Spouse