Optimizing string replacement program that uses recursion

I have the following string replacement program for a string of size 256:

I am replacing the string

"\'"

with the string

'

Please suggest any modifications if needed or any mistake I have done.

#include <stdio.h>
#include <string.h>

int replace_str(char *SrcStr, char *SubStr, char *RepStr, char *FinalStr )
{

    static char buffer[256]="";
    char *TempStr= NULL;
    char *Tmp2 = malloc(250);
    memset(Tmp2,0,256);

    int ret = 0;

    TempStr = strstr(SrcStr, SubStr);

    if ( TempStr )
    {
        memcpy(Tmp2,TempStr,strlen(TempStr));

        strncpy(buffer, SrcStr, TempStr-SrcStr);

        buffer[TempStr-SrcStr] = '\0';
        sprintf(buffer+(TempStr-SrcStr), "%s%s", RepStr, Tmp2+strlen(SubStr));

        puts(buffer);
        free(Tmp2);
        ret = replace_str(buffer, SubStr, RepStr, FinalStr);
    }
    else
    {

        memcpy(FinalStr, buffer , strlen(buffer));

    }
    return ret;
}


int main(void)
{
    char *str1 = malloc(256);
    memset(str1, 0 ,256);
    memcpy(str1, "pra\'dipta\'kumar\'rout",strlen("pra\'dipta\'kumar\'rout"));

    char str2[10] = "&apos;"; 
    char str3[3] = "\'" ;
    char buff[256] ={0};

    replace_str(str1, str3, str2,buff);

    puts(buff);

    return 0;
}