If I understand you correctly, your Mother-in law was the owner of a life insurance policy with her son as the beneficiary?
Her son (your husband) died and then she cashed the policy in?
If this is in fact the case, you have no legal right to any information on the policy. ONLY the owner(s) are entitled to policy information.
FYI:
Who was the owner(s)?
Who was the insured?
Who was named as pri**** beneficiary and contingent?
(actually, the beneficiary information is irrelevant if the insured is still living and the owner cashed the policy in. Beneficiaries only come into play if the insured dies. The owner can cash the policy in whenever they feel like it before the named insured dies).
stu