I think thumbscrew’s enquiry referred more to the normal State Pension rather than the “bereavement Allowance” (which was previously called a “widow’s pension). The former is payable until the recipient dies. The latter is payable only for a year following the spouse’s death (it is payable to bereaved men as well as women) and the recipient has to be over 45 but below State Pension age.
Until 2001 women could receive a State Pension based on their husband’s NI contributions. This is no longer the case and they now receive it, in line with men, based on their own NI contributions. There is nothing barring them from claiming a State Pension if their husband had taken his own life but, in line with all other women, they do not receive it until they reach State Pension retirement age (which is currently being increased but for someone born in January 1954 is roughly 65 years and three months).