At first thought, I believe Makima would win and this seems to be a stomp matchup.
Makima has multiple ways to escape being frozen solid, assuming this occurs via ice-based abilities. She could rely on an intangible devil to noclip her out, such as Beam or Princi, or have the ice thawed by the Flamethrower Hybrid. Makima's win cons stem from her 17x reaction speed advantage combined with automatic precognition, allowing her to easily evade initial attacks and deploy minions, whether Hybrids or Zombies, to absorb environmental damage close quarters wise. Plus, her telekinesis could effectively damage Iceman by blowing holes into him. She could also remove him from the battlefield using the Hell Devil summon or seal him with the Snake Devil, among several other wincons enlisted in her controlled abilities.
I don't believe this matchup is valid because Iceman doesn't realistically have a win con. It's important to note that if Makima manages to fatally injure Iceman even once initially, she will view him as inferior, triggering her Conquest ability. A single severe injury is all that's required.
The starting distance follows SBA, meaning they begin 4 km apart. Given this, Makima's typical battle tactic would be to deploy her minions, stay hidden, observe the opponent, gather information through clairvoyance and strategically plan her moves. Overall, this matchup feels quite random and not particularly engaging to me. Not my cup of tea, I will observe and correct if needed though.