honeyisazombie

This does not sound promising.    Have you revealed this to your relative?  Learning enough to become even minimally knowledgeable about a very specific niche of the collectibles market takes time.  Hence, what value do you place on your time?  Would you be happy working for, say, $0.25~0.50/hour?  The best route for you and your relative to take may be to sell the entire collection to someone who does know what he/she is doing.
Regardless of which route you choose, putting together an inventory list (exact titles and issue numbers) is always a good first step, supplemented by as many group or individual-item photos as you have time for.  If you're willing to divulge your zip code, folks who visit this forum may be able to recommend someone in your neighborhood/town who could look over your relative's full collection and give you a rough estimate of its market value.  Good luck! 

Ok, so there's a lot to unpack here.  First, there are a few Dr. Strange (1974, 2nd Series) books that have some value.  However, that is in higher grades (and if already professionally graded and encased in plastic holder, which of course costs money to have done).  Now, if the #174-#186 are the 1968, 1st Series (as pictured below), those have some value (and again, the better the grade the higher the value). 
To give you a sense of what you're up against, I've picked up almost a full run of volume 2 books (like the #3 you have pictured) for between $0.42 and $3 at garage sales and here on the Boards over the last couple of years.  The condition of those books is what you might expect at a garage or Estate sale - decent but have clearly been read.  Your books might be at least a little better.
Make a list of all the books (I use Excel) if you haven't already.  Then I'd encourage you to take a look at a site like MyComicShop.com and search the books you have.  They'll have them for sale in various grades (and some will be "raw" like your books - i.e. not "graded") so you'll have a general sense of what they're trying to sell them for so you can at least ballpark a number.  
Good luck!  Keep asking questions in this thread and folks here will try to help.