Help!!! Is it right to collect transport fare from my girlfriend's brother?

Dear emeh
I am an avid reader of your blog and I need advice from Miss petite nigeria house on this issue. I work with a prestigious bank and am ok. I have been dating a girl since january and we are really serious, I have introduced her to my parent nd I knw hers too most especially her mom nd sister, last weekend she took me to her brother's house for introduction, when leaving her brother gave me transport fare in an envelope which I politely rejected( don't knw hw much in d envelop sha). The brother took no harm with the expression on his face. For 3days after the visit my babe condemned me for not collecting the cash from his brother tho its been settled but next weekend we are visiting another brother's house, if am given transport fare again, should I collect?
Please re broadcast to the MP house. Thanks emeh