Does wearing the niqab with the intention of not working invalidate the intention and prevent reward, especially given that it will increase the father's anger?

Wearing the niqab and covering the face and hands in front of non-mahram men is obligatory, especially when there is a fear of fitna (temptation/strife). If refraining from an act that is impermissible in Sharia cannot be achieved except by wearing the niqab, then its obligation becomes even more emphasized, because that without which an obligation cannot be fulfilled is itself obligatory. This intention does not nullify the reward; rather, it is a seeking of God's pleasure. Obedience to the father is not obligatory in going to a job that is impermissible in Sharia, except out of necessity, because obedience is only in what is right. It is advised to be kind to the father and help him with what you can, through work at home and outside, if the conditions are met and there are no impediments.