There's nothing more frustrating than wanting to return something, but being unable to because of store policy. If your mom is very particular or you aren't totally confident about your gift, you might want to prioritize purchasing items that can be returned easily. And even if an item can be returned, you should check the retailer's site for the length of the period during which it can be returned. Note that if you're shipping your mom a gift, returning the gift might be more complicated regardless of policy, so consider playing it safe.