Full single player game almost in Alpha state. A publisher asks for multiplayer. How much insane is to even evaluate the deal?

Premise: I am an experienced programmer, so I already have my thoughts on this, but I was just too curious to know the general thought on a situation like this one.

So, we are an indie team, and we've been working (for free) on a game for more than 2.5 years now. The game has been entirely designed and programmed to be single player, it has a lot of systems (it merges both survival and rogue-like mechanics) and we are in pre-alpha state at the moment, with Alpha not too far (we expect to complete the game by the end of December).

The game is developed in Unity, the team is composed by 7-8 people, and I am the only programmer.

Apparently, despite being extremely liked both by players and scouts/publishers, we are struggling to find funds (this is the first game of "the team"). Suddently, a publisher asks for multiplayer feature.

I won't mention the amount of money, because we don't know it yet, yes, but also because I'd like to know from you:

A) Do you think it is insane to even evaluate this request?

B) How much would you ask for a similar request?