So first the easy part. The warning that says you should access LAYOUT_INFLATER_SERVICE in a static way wants you to change it from context.LAYOUT_INFLATER_SERVICE to Context.LAYOUT_INFLATER_SERVICE (capitol 'C') so you are accessing the variable through the class rather than the instance.
Second, the null pointer exception is definitely happening on your 'context' variable, so whenever you are instantiating ExpandListAdapter, you are giving it a null value for context. You didn't give me that code, so I can't look into it, but I would recommend instantiating your ExpandListAdapter in onCreateView or onViewCreated. If you are creating this in an activity, pass it a reference to the activity (i.e. 'this'), and if you are creating it in a fragment pass it a call to getActivity(). This won't work though if your Fragment isn't attached to the activity though (which may be your issue).