Why does the government only pay bereavement benefit for 52 weeks when my husband is not coming back ?

My husband recently passed away and I was awarded bereavement benefit for 52 weeks total amount of �91. per week.the tax office have now changed my tax code from 746L to 264. therefore my tax has trebled,is this right? i`m trying to get back on my feet but it seems that there are bigger hurdles around every corner,can anyone help point me in the right direction.