Yes it is possible with just site-to-site ipsec tunnel between PIX and ASA.
Crypto ACL at Home A just have to say from local subnet to any
Crypto ACL at location B just have to say from any to remote subnet at Home A.
At location B, you would need to configure NAT on the outside interface for Home A subnet, and also configure "same-security-traffic permit intra-interface" so u-turn can be done for internet traffic from Home A.