A lava-lit path or road, which, depending on the construction method, can also serve as a floor heating system.
This road is lit with lava and "kept warm".
Here are two cross sections:
With underfloor heating:
without underfloor heating:
although the first one makes more sense in a house.
this is what it looks like at night:
even if this is quite simple to obtain it is rather less good for survival because you need a lot of lava.