I don't know why there would be so many in yours, mine as 109 files most are 0KB and a max of 494KB, for me that isn't an issue (1.54 MB (1,614,854 bytes). Have you recently done an install and or a program update ?
What Avast Program/s do you have installed ?
What is the date span of these files ?
Why this location is used rather than the C:\ProgramData\AVAST Software\Avast\log folder is beyond me. Even trying to open it results in an error, so it looks like it it protected by the Avast Self Defence Module.