Is the 5 V rail of an LM298 reliable?
The L298 is obsolete. Really. Don't use it anymore. It's inferior in every way I can conceive to more modern competitors. Compare this answer. The LM7805 is kind of in the same category: It's an OK linear regulator, if you have absolutely no alternatives.

With that out of the way: you do NOT want to run your microcontroller off the same voltage regulator that is used by your H-Bridge driver. There's probably a reason the module containing the L298 (you're confusing the chip L298 with a module that contains that chip in your question) comes with its own voltage regulator, and its that there will be highly variable loads on that supply.

Since this is clearly a least-cost solution (why else use an obsolete chip?), the voltage regulators won't be dimensioned to be reliably stable under these loads – they will be sufficiently stable for the L298 and support electronics, but not for your MCU.

So, get a separate voltage regulator for your nodeMCU; by the way, nodeMCU is just the firmware running on an ESP chip, and you're again confusing chip with module. 

The espressif ESP8266ex, which is running NodeMCU, is a SoC that takes 2.8V to 3.6V as input voltage. So, unless there's yet another voltage regulator on the wifi module you have, you cannot even use the LM7805 – as that outputs 5V.

So, get a linear regulator that outputs 3.3 V; you don't need multiple amperes of current to drive a node. Make sure you've got at least 200 mA reliably (which probably means dimensioning your linear regulator for 500 mA or so), that would be sufficient, according to Espressif's datasheet.

There's plenty of linear regulators to pick from, most of them much nicer in reaction to load shifts than the LM7805. If in doubt, consult for example TI.com and look for linear regulators with your input voltage, 3.3 V output, and a package you can work with (probably TO-something or *DIP-Something). They have good parametric tables with which you can play. Because you waste (11 V - 3.3 V)·(500 mA)~= 3.5 W of power as heat, you want something with less than 30 °C/W  thermal resistance – or else your regulator will get more than 100 °C hotter.

That kind of indicates that for a voltage jump so big, you'd want a switch-mode regulator. Again, plenty of choices to pick from. Again, TI.com (and competitors) have a parameterizable search. You probably want a simpleSwitcher module from TI, as it comes with all things integrated. The TPSM84203 looks like a good choice.