The Nyasa languages are an apparently valid genealogical group of Bantu languages

Bantu languages

The Bantu languages constitute a traditional sub-branch of the Niger–Congo languages. There are about 250 Bantu languages by the criterion of mutual intelligibility, though the distinction between language and dialect is often unclear, and Ethnologue counts 535 languages...

. With the reassignment of a couple Guthrie Zone N languages to other branches, Nyasa is essentially synonymous with Zone N. The languages and their Guthrie identifications are:

• Tumbuka
  Tumbuka language
  The Tumbuka language is a Bantu language which is spoken in parts of Malawi, Zambia, and Tanzania.The language of the Tumbuka people is called chiTumbuka — the chi- marker in front of Tumbuka means “thing”, “concept”, and is understood in this case “the language of ”...
  
  (N20) [excluding Senga dialect]
• Chewa (Nyanja) (N30)
• Sena (N40, reduced): Nsenga
  Nsenga language
  Nsenga, also known as Senga, is a Bantu language of Zambia and Mozambique....
  
  , Kunda
  Kunda language
  Kunda is a Bantu language of Zimbabwe and Zambia, with a few thousand speakers in Mozambique....
  
  –Nyungwe
  Nyungwe language
  Nyungwe is a Bantu language of Mozambique. It is used as a trade language....
  
  , Sena
  Sena language
  The Sena language is spoken in the four provinces of central Mozambique : Tete, Sofala, Zambezia and Manica.There were an estimated 900,000 native Sena speakers in Mozambique in 1997, with at least 1.5 million including those who speak it as second language.Sena is spoken in several dialects, of...
  
   (incl. Podzo, Rue)

Poorly known Mwera-Nyasa

Mwera (Nyasa) language

Mwera Nyasa is a poorly attested Bantu language of Tanzania....

is N20 and presumably belongs here as well. Nurse (2003) has doubts about Nyungwe and Sena.