Can't make it to interview

Just this morning I received an offer to have an interview for Brown university. However, the only place to have the interview is a two and a half hour drive away. My dad is away working in another state and my mom isn’t available to take me. Is this a typical distance for an interview? And will it look bad if I decline for this reason? Thank you.

That seems very far to travel to me but it’s possible there are no alumni available in your area.

I would be upfront with your interviewer that you do not have transportation to attend in person, but ask it they would be open to doing a skype or phone meeting instead.

The explanation you provided, along with a suggestion to conduct the interview over Skype/FaceTime would be perfectly acceptable, IMHO.