A lot of people would love to have that as their commute. Even though the distance is far its probably an easy drive. I don't know where you work but leaving the Galleria area to anywhere during afternoon rush hour takes forever. I've had some days where it took me 20 minutes to go 2 miles due to cops stopping traffic for cars to get out of garages.
Like you said internships are hard to come by in certain industries so she should do whatever is necessary to attend. She should be happy they are firstly paying her and second she doesn't have to take a bus to get there. I'm sure there are countless other students who would attend for free and/or take public transport to get there.
I don't know anything about Texas geography; but I will say as someone who's held two internships and whose friends have held many more than that; they rarely pay. If it's even remotely related to her field and its paid, take it.
It's what they always say: nowadays, you often need experience to get experience. I would tell you straight up she would be foolish to not accept the internship if it would help her get needed industry resume buff to help her going forward. Internship money/commuting "struggles" is irrelevant in the grand scheme, as long as it is relevant. I did a summer internship in pharma (don't like bio) and lived in a trailer park in Long Island without a car for the first of my two internships. Now, I have a fantastic gig after graduation. I say this not to brag but to illustrate that taking the bullet will be worthwhile.
People drive longer distances for a 7 dollar an hour dead-end hard labor job. Tell your sister to humble up.
I live in Sugar Land, so I have an idea of how traffic goes around here. In the morning, it's rush hour going towards Downtown. She won't have any trouble coming from Beltway 8 South to 59 and into Sugar Land. In the afternoon, she may have to deal with traffic on Beltway 8 North though. But it's still not a bad commute at all.
If it's in her career of choice and she sticks the class and social landing well-enough to either get an offer or an industry referral she should be driving to Sealy or El Campo. If Memorial refers to like Westchase/Beltway 8 I would think that's a nicer commute than going into Downtown or Greenway; but I've only driven to Sunoco during mid-day or after hours..
I used to drive from Friendswood to Cypress everyday (not on the beltway) for 6 months for a job. That commute is a cake walk.