Your mom has a right to be concerned, even if it is unlikely that a cannister will leak. Water leaks can be disasterous to a house. But really, any part of a tank can leak...maybe you shouldn't mention that to your mother.
Here is something that will give her some piece of mind. It is what I did to give myself some assurance that no leaks have developed around my cannister filter...
First, I put my new cannister filter into the largest and deepest Rubbermaid tub that I could find that would fit inside my stand. That way any leak would be safely contained, at least for a while. But even the biggest tub that Rubbermaid makes will not hold 75 gallons. So I added a "moisture alarm", and put the sensor into the bottom of the tub and the speaker outside the stand. If you are not familiar with moisture alarms, they are small electronic devices sold in any good hardware store (I bought mine in HomeDepot for about 10 bucks). They are mostly used around hot water heaters, or washing machines.
Find the type that has the sensor on a little wire so that the sensor can be inside your stand and the battery/speaker part outside the stand, for best sound. If any moisture hits the sensor pad, the speaker will produce a loud alarm and you will be warned that a leak has developed.
The only drawback to this is that someone needs to be home to hear the alarm AND must know how to turn off your filter and stop the flow of water into it. Otherwise, your tank may drain (even if someone unplugs it) and kill your fish. I showed my roommate how to do all that, so I am pretty much safe.