My dad swears at my mum while she is fasting and she doesn't know what to do so she gets angry and swears back at him, but now she wants to know how to avoid him so can you help me and tell me how this can be done.

Its not a matter of outward avoidence. It's the inner that should be avoiding the trap. Fasting is a time for reflection. So your mom needs to learn how to ignore it. That is the only true way to deal with it. It falls under a term " killing with kindness".

That is the only true way to stop it from affecting her.

Yeah I told her but as always when ever its ramadan my mum makes food for him to take to his work place but he always leaves it behind and when he returns back home he has a go with my mum and blames her for not having iftar. My mum was really upset today and she gave up on him so is there any other way were my mum can have peace without breaking up with him?

Not that I can think of except by removing herself from the situation. Like staying with family during this period. Other then that she has to deal with her own anger issues and not get caught up in his.