I’m assuming there are not a lot of income producing assets in Moms estate… the money from her checking and savings would not be taxable to her heirs…. The inherited IRAs would be taxable to the beneficiaries…. In your case, the estate of the husband.

Was there a will? Was your client the sole heir to her husbands estate? Did she receive the money? If so, I’d include the 1099R  on your clients return (so the tax is paid). 

the 1041 would be a pass through to the husbands heirs….  If there’s nothing else  in the estate and it was a full distribution I probably wouldn’t bother with a 1041…. If there’s going to be annual distributions from the inherited IRA they should make sure the IRA trustee retitles the account