So long as the handset is just a vanilla CDMA handset (no 4G LTE), either
Selectel or
BYO Wireless should work for activating both her current handset and porting her existing number. Selectel is the longer established of the two companies.
Five things to note, however:
1) Sending pictures through a text is called MMS service (as opposed to SMS which is text only), and MMS requires data.
2) Selectel allows CDMA roaming off Verizon, but their cheapest plan (Yearly - about $6.25/month) does
not include MMS.
3) BYO Wireless is Verizon native network only, but their cheapest plan ($5/month) does include MMS.
4) So long as a CDMA tower is in range, an E911 emergency call can still be placed even if there's no off-network roaming from the provider.
5) With the US CDMA network, even if you're off-network and cannot roam with your current provider, regular calls can still technically be placed through the
ARN for a price.
There's technically Page Plus as well which has PAYGO and reasonable rates that would pop in under $5 a month for her needs, but they're owned by the same company that does Tracfone and NET10, and service support and billing
stink. As such, I don't include them in the guide anymore. Unfortunately, there's really not too many well established, good, frugal, Verizon MVNOs.
It's going to be very possible to get her line cost
well under $10/month, but one of three compromises will be required depending on the provider: roaming, MMS or customer service. I'd personally recommend sacrificing either roaming or MMS support long before considering sacrificing customer support.