Re: Break salah
Peace TLK Bhai,
Allow me to share my knowledge 
It is said that if a person is offering Nafli Salaath then he/she can answer either father or mother and that is in case if there is an emergency. However, in case of obligatory Salaah, it is preferred to shorten (brief) the Salaah to answer parent. Even if they keep calling while a person offering obligatory salaah then he/she may say a loud “Subhan Allah” or read loud "whatever verse/surah he/she was reading so that the parent may know that his/her son/daughter is offering Salaah.
It is not recommended to break obligatory Salaah upon the call of either father or mother. However, breaking Nafli Salaah upon call of mother is acceptable in view of many scholars as many of them also said that if you don’t answer to your mother then it is counted as haraam.
Almighty Allah knows best.