My mum always has something bad to say about immigrants. My wife is an migrant what ca I do?

My Mum loves my wife and daughter but it is getting embarring when my Mum frequently goes on and on about immigrants and how they are destroying this country. She has no clue what she is talking about and jumps on any tabloid story of immigrants getting handouts. I have often tried talking with her and explaining that as a well developed society it is our obligation to look after asylum seekers who are really not here out of choice but desperation, of course a small number play the system but even so they are probably doing so because life where they are from is so bad. I also try and make her understand that many immigrants are economic migrants and only here to work not live on benefits. I am avoiding visiting my parents as I do not want my daughter to hear this constant stream of rubbish and it is becoming uncomfortable because my wife is understandably becoming less tolerant of my mums absurd views. My dad does not get involved at all and I am sure he is shocked at some of the ridiculous things my mum says. I really do not know how to approach tackling this, my mum loves my daughter and my daughter my mum but I can't risk my daughter picking any of this up. On every visit at some point the conversation degenerates to immigrant bashing and I am just fed up with it. My wife and I do have a little laugh at my mums ignorance but it is a serious situation and somehow needs addressing - please help?