I would suggest when you send out your resume that you include a cover letter explaining the gap. Many people have gap periods due to a variety of reasons.
You can state that you attending college to complete your degree while being a family care giver for a serious illness. Any reasonable hiring manager would understand.
Also you could utilize your college career placement office - they would be best able to guide you on how to note this on your resume and/or cover letter. You pay for tuition and the placement office at your college is some of what you pay tuition for. There should be no cost to use them (when I was in college I worked parttime at our placement office - the staff there was excellent).
You can also go to a recruiter - call them and explain your situation. Most recruiter work where the hiring company pays for the service not the individuals seeking employment. They are also experienced and benefit by placing people (that is how they earn their pay so they are motivated to place you).
And jespah gives good advice - don't feel down on yourself - you did an awesome thing shows what good character and compassion you have.