The answer to your question is "Tú me dariás una respuesta."
The first option, "daría" is used with third person subjects such as "el and ella."
The third option, "daríais", is a conditional applied to the second person, "vos", in Iberian Spanish. This is the type of Spanish that still conserves the ancient replacement of "usted", a more respectful form of address in the second person, with "vos". It is a Spanish form used mainly in Spain and some areas of Central and South America, namely, in Argentina, Chile, Uruguay, Paraguay, and Colombia.
Therefore, the use of "darías" goes hand in hand with the second person casual "tú ".
Tú me darías una respuesta.