(advice sought on who can sign unfiled returns and Forms 870 and 872 after taxpayer’s death; decedent, non-filer, died intestate with bank account as only asset held by daughter and spouse; IRS determined that daughter could sign unfiled returns in accordance with I.R.C. Sec. 6012(b)(1); daughter should submit Form 56 to document fiduciary relationship as personal representative of mother’s estate and allow daughter to file Forms 870 and 872).