Husband's company went belly up, after tax pension plan was taken over by feds. Been drawing from funds, on his death it started coming to me... is this taxable to me?

When the company husband was working for closed; we learned that the post tax pension plan he had been paying into had be moved to Fed.Gov't control by PBGC.   His choices were lump sum, 2. for his life span... 3. Upon his death, it would continue paying spouse until her death.   We chose option 3 despite a lower dollar amount per month.   Now he has passed, it has moved over to me; but Turbo Tax is asking me questions that I am not sure how to answer.   1. Such as what I will do with the money.   2.  If I made any after tax contributions to this retirement plan, then this amount may NOT be the correct taxable amount.   (His contributions all those years ago, were post tax... so why am I being questioned about some of this may be taxable now?)   Scared!!!  Option 3 on the "Lets Figure Out How Much is Taxable screen is indicating that the entire amount may be taxable!!!  WHY???