The Concentration camps were guarded mostly by special units of the SS-Totenkopfstandarten (Deaths Head). Early in the war these units were made of volunteers and were equipped with military surplus by commanders who didn't want to sent vital hardware to what was seen as 'prison detail' duties. Karabiner 98k's would be the most likely weapons of such equipped units as it was the primary rifle of the German army at the time, but outdated Gewehr 98's may also have been used by camp guards as they were issued to some SS units. Due to the same resistance Totenkopf units were denied heavy equipment. This also lead to multiple units using captured weapons for prolonged periods like the 3rd SS Panzer Division Totenkopf which fought with predominantly captured Czech weapons. In 1940 the SS was also limited in who it could accept, with any man of military age already being claimed by the army. This forced the units to accept the very young, very old, and from its own guard units leading to mass migration of soldiers from Totenkopfstandarten into front-line Waffen-SS units. On average there were very few machine gun or submachine guns within the SS-Totenkopfstandarten in 1939.

In terms of later war weapons the Totenkopfstandarten were still limited by their founding years. Some were still equipped with captured Czech weapons such as the vz. 24, Maschinengewehr 30 (both captured and built under license), and ZK-383's (built in Czechoslovakia specifically for SS units). In Auschwitz in particular the garrisoned SS-Totenkopfverbände guard consisted of 8 - 10 companies plus officers and other non-combat personnel. Known shipments to this unit include low quality Czech peoduced MG 26's, MG30's, MG37's, and less than adequate heavy weapons likely due to the low training of security units. The average soldier was predominantly equipped with standard issue Karabiener 98k or Gewehr 43/Karabiner 43 variants (in small numbers at the late stages of the war). Maschinenpistole variants (the 34,35,38,and 40) would also be part of a German units standard equipment at various times although in low numbers compared to rifles. STG-44's may have also reached some camp units although with only half a million produced before the wars end it is likely they were directed to front-line units on the Eastern front, as well as to units stationed around the Channel islands and expected Western mainland-landing locations.

In the very final days the 'real' SS members began to flee the camps and were replaced by conscripted Volkssturm known as SS-Mannschaft. These soldiers were very poorly equipped and often too young, old, or disabled to have been called into service earlier in the war. Most Volkssturm were given a Karabiener 98k if available but even more outdated Gewehr 71s and Steyr-Mannlicher M1888s were also widely distributed. Some luckier members received submachine guns like the Volkssturmgewehr or MP3008. With barely any training such replacements were expected to hold off the Allies invasion long enough to let proper units escape and regroup or rearm.

If you're asking abut the recorded weapons at the time of liberation not a huge amount is known as the final guard units of Auschwitz as they fled the camp on a death march to Wodzisław Śląski with around 60,000 prisoners. The same SS units were caught in Bergen-Belsen camp by British and Canadian forces and surrendered without a fight.

A wide array of pistols were also in use within the camps both a side-arms and to execute prisoners more immediately (mostly those who would otherwise cause trouble). SS soldiers are known to have bought their own pistols and models including the Walther's PPK, PP, P38, and Mauser's C96, HSc, Luger P08, and even the Browning Hi-Power (manufactured under the designation P640b) were known to have been used by the SS.

tl:dr - The armament of a standard German unit changed frequently and the unit stationed at the camps routinely traded men with frontline SS units making an exact list of weapons difficult.