In Canada and the United States ,for a fee, you can use the Medical Information Bureau (MIB) Policy Locator Service to help you find a lost policy. Some companies have their own searchable databases.
You are looking for clues: review bank statements for withdrawals; contact friends; did she have an insurance advisor?; etc.
Once found a review of the policy will determine if there is coverage or cash value that could be used.
If you have further questions please do not hesitate to contact me.