The first thing you need to do is to inventory the family pictures to see what you'll be scanning. You will certainly have prints, but will likely also have negatives and possibly slides. The negatives are likely to be a reasonably wide range of formats. Only after you've found out the range of sizes and types involved can you make any intelligent decision on what scanner to get.
That said, you will probably find that your best option will be a good quality flatbed scanner that has good film scanning capabilities. One likely candidate is the EPSON v500 and newer v600. These are very good scanners for prints up to 8x10 and film in sizes up to 120 roll film. This will cover most amateur formats used by cameras made since WWII and many of the earlier cameras.
I'm in the middle (~1500 images behind me and another 1500-2000 to go) of a similar project that is a 50/50 mix of old family pictures and nearly 50 years worth of my own personal images. My family pictures include quite a number of negatives shot on antique roll film and pack film formats distinctly larger than 120/620 and my personal work includes a most number of 4x5 negatives and transparencies. I choose to get an EPSON v700 which, while being able to deliver a bit better image quality, can scan the larger film formats.
Use the search function to search this forum for other posts on scanners. You should find several from which you can glean info and opinions. I also recommend that you drop by The Rangefinder Form (
Rangefinderforum.com Portal - Rangefinderforum) and do a similar search. There have been some excellent recent discussions about several of the EPSON scanners, both current and recent models, along with models from other brands.
You'll find a high bias toward film-only scanners (aka "dedicated film scanners"). While some of these can deliver slightly better film scans than models like the EPSON v700, none can scan prints and most require significant skill in crafting carriers for odd old formats. "Shoe horning" odd formats (e.g. 110, 126, 127, ... to name a few common amateur formats) into the carriers for flatbeds, like the EPSONs, is relatively easy and you can always just lay the film on the glass without a carrier.