Asking a Polish mums acceptance

My girlfriends dad isn't around so I'd like to ask her mum just for old times sake if i can ask her daughter to marry me. I'm trying to keep it a surprise so I can't ask her friends to translate for me, would the following be ok as a simple sentence?

Chciałbym prosić o rękę! Monia!

I'm wanting it to say, I would like to ask Monia to marry me.

If this is wrong or there's a shorter easier line please let me know! And any fast replies would be great!

Thanks

Shorter.. no :) but more natural would be something like this:
Chciałbym poprosić Monię o rękę

Thanks! Her mum said yes and my girlfriend said yes!!

Are you marrying both?

congratulations.

:-) I'm happy to hear that! Congratulations!