One nice thing about the web is that one's hair color, and hair quantity, is irrelevant.
Let's assume the face amount of the insurance was $100,000, and the deceased died 6/30/05. As it takes a while to get the death certificates, let's say the death claim was filed on 7/31/05 and we'll look at two alternatives: 1) the insurance company issued its check on 8/15/05, and then alternative 2) the insurance company paid the claim through a retained asset account on the same date and sent her a checkbook instead of a check.
Some insurance companies pay interest from the date of death until they cut the check or put the money into the retained asset account. (Others do not, unless required to do so by state law, sometimes after a set time period, say 30 or 60 days from the time a claim is filed.)
Given the fact that interest rates now are reasonably low (assume 4%), IF the insurance company paid interest from date of death, the check it cut in alternative 1 would be for $100,000 PLUS 45 days interest at 4% which is $500, for a total of $100,500. That check does not bear interest, period. Whether she deposits it or not the insurance company would report to the IRS that it paid her $500 in interest in 2005. She gets the death proceeds of $100,000 income tax free, but may have to pay taxes on that $500 of interest; that depends on her tax rate and she adds it to her other income and if she has enough other income, it would be taxable on her 2005 return, whether she cashes the check or not.
Now IF the deceased's estate had exceeded $1.5 million (that goes up to $2 million for those who die on or after 1/1/06) and the deceased was not the beneficiary's spouse, there may be federal estate tax; generally insurance beneficiaries have to pay their share, but my guess is that's not her situation. (It's what some little old lady may have told her, in ignorance.)
Let's do alternative 2 -- if the insurance company paid the money thru a retained asset account, it would have placed the $100,000 (and if it paid delayed settlement interest, the hypothetical $500) into the account on 8/15/05, and that account would have started earning interest at once and will continue to do so until she takes the money out of the account. Each year it would report the amount of interest she earned to the IRS, just as a bank would. If she takes out some of the money, then there would be less left on which she'd earn interest, and thus less interest she'd earn.