I might be stupid but still trying to understand PIC
Can I store two fixed temperature values in EEPROM and compare the measured value from thermistor?

You don't need the eeprom, when you do a temperature A/D conversion, the result is placed in the file ADRESL or ADRESH, you can move these results into ram memory, and do another conversion for the preset temperature, then subtract one from the other. And its much easier with a Lm35 than a Thermistor.

 

And its much easier with a Lm35 than a Thermistor.

The TS has made it clear that "easy" is not the goal of his assignment. Quite the opposite, I'd say.

 

Well good luck to him/her then.......