Almost definitely, the second speaker is saying "I can make steak and chips", meaning they will cook/prepare steak and chips for both speakers to eat for dinner.
Considering the context of your example, the second speaker is offering a solution to the problem "What are we going to eat?" To say "I can do ..." definitely sounds like they are offering to provide the food, as opposed to "let's have ...", "how about ...?", or "I feel like ..." which would have been used if they were just throwing around what they felt like eating. They've used an idiomatic pattern in this case that is applied in cases where the replier is offering to prepare the meal.
In addition, steak and chips is British English. In British English, "I can do [food]" almost always means "I am happy to make [food]".
In British English at least, it is rarer to say "I can do [food]" to mean "I would like to eat [food]", because "I can do [food]" might seem to carry an implied sense of entitlement, and risks coming across as rude/self-important, although in some cases this entitlement is entirely justified and then you may expect this usage; a vegetarian may say "I can do that" because they know the suggestion to be a meal/venue with vegetarian options. A spice-intolerant person may say "I can do the korma but not the vindaloo" because the spicier option would ruin their night and week, so they actually can't eat it.
"I could do [food]" is more common and more generally accepted as being polite for the meaning of, "I would like to eat [food]" ("could" is less demanding than "can", and the idiom "can do [food]" is already loaded with the "will cook [food]" meaning).
Of course in some parts of Britain, as in any country with diverse language varieties, you might see some local or social dialects preferring "I can do [food]" to mean "I would like [food]", but this seems to be the minority across the language. It's likely your test's intended meaning is "I can prepare steak and chips for us to eat", unless your test has tricked me by planting a British expression ("steak and chips") into what they intended to be an American English conversation.