Well, assuming an E-100 was ever fully built, it still probably couldn't. It's top armour may have been thicker than that of other German tanks, but that wouldn't have helped it much against the many bombs and rockets the Allies would throw at it when they saw it appear... And if it wasn't killed, the crew would probably have abandoned it already because of the intensity of the aerial attacks.
No. No tank of WW2 had its own AA platform for self defence. Some had an MG fitted on the turret for defence against aircraft as well as close infantry defence for the commander. Certain tanks were fully converted to AA tanks, though, with the specific purpose of protecting other tanks from air attacks.
Aircraft would surtenly destroy a Maus, don't think it would be very hard at all(i've seen movies of Stuka's attacking tanks and even a near miss would lift the tank and destroy it.....don't want to know what a 250Kg bomb would do to the deck of a maus.... BTW. I think the idea of Tanks equiped with AA guns would have the same effect like those U-boats called Flak-Traps....tanks would not hide and seek anymore but just wait for aircraft to arrive with the result that it would be more easy to spot and in the case of the maus make it an even better target (as it was a BIIIIG tank)! Don't get me wrong AA guns on tanks can destroy aircraft but once fired the tank would make an excelent target....
I was referring to the rockets used by Allied fighter-bombers. As for anti-aircraft tanks, these are usually equipped with low-caliber, fast-firing weapons such as the 2 cm Flakvierling of the Wirbelwind or the 3,7 cm Flak of the Ostwind. Large-caliber weapons, such as the 8,8, 10,5 and 12,8 cm Flak were useless against low-level aircrafts. If I recall correctly, each German Flakpanzer unit had eight vehicles in total, which would present a fairly dangerous targer for any low-level aircraft.