Está or éste

Está or éste
 

Está usted en Madrid con su familia?
No mi marido está en Londres con mis hijos.

In the reply marido está not marido éste. está is feminine

está = "he/she/you (singular formal)/it is". Note that the mandatory accent mark on the second syllable indicates that the tonic accent is on the second syllable. Verbs do not have gender in Spanish.

In the first sentence: ¿Está usted en Madrid con su familia?

está = verb, "he/she/you (singular formal)/it is"
usted = pronoun, explicit subject "you (singular formal)"
en Madrid = prepositional phrase of location, "in Madrid"
con su familia = prepositional phrase of manner/circumstance, "with your children"

In the second sentence: No, mi marido está en Londres con mis hijos

no = adverb, indicating negative reply. The rest of the sentence explains why.
mi marido = noun phrase, explicit subject, "my husband"
está = verb, "he/she/you (singular formal)/it is", matches explicit subject, "(my husband) is"
en Londres, prepositional phrase of location, "in London"
con mis hijos, prepositional phrase of manner/circumstance, "with my children"

The demonstrative adjectives/pronouns este/éste, esta/ésta, estos/éstos, estas/éstas, and the neuter demonstrative pronoun esto all have their tonic accent on the first syllable.